JP5864133B2 - Program and server - Google Patents

Description

  The present invention relates to a program.

  2. Description of the Related Art Conventionally, there is a mail server that receives and transmits an electronic mail on a network through SMTP (Simple Mail Transfer Protocol).

  Normally, when such an e-mail server receives an e-mail addressed to a user under server management, the mail server stores the e-mail in a storage area (so-called local delivery). On the other hand, when the destination of the received e-mail indicates an address of another mail server, a process of delivering the e-mail to another mail server is performed (so-called remote delivery is performed).

  When the mail server receives an e-mail reception request from the terminal through POP (Post Office Protocol), IMAP (Internet Message Access Protocol), or the like, the mail server performs processing for transmitting the e-mail in the storage area to the terminal. (See paragraph 0030 of Patent Document 1).

JP 2000-228673 A

  However, when a conventional mail server receives an e-mail addressed to a user under server management, it sometimes uses a storage area when storing the e-mail. For example, if an e-mail containing an attachment is received and then another e-mail containing an attachment with the same contents is received, each e-mail is individually stored in the storage area even if the attachment has the same contents. Since the data is stored, the storage area is wasted, resulting in an increase in the usage amount of the storage area.

  In particular, in recent years, files such as image data and audio data are often attached, and e-mails including attachment files of tens to hundreds of megabytes are transmitted and received, and storage for storing e-mails It is expected to save space.

  The present invention has been made in view of the above-described problems, and provides a program for a server capable of saving the amount of use of a storage area for storing an e-mail addressed to a user under server management. There is.

  (1) The present invention is a program for a server that performs processing for storing received e-mail in a storage area and transmitting stored e-mail, and a receiving unit that performs processing for receiving e-mail; When an e-mail addressed to the user under the server management is received, the e-mail is received when the e-mail reception request is received from the storage processing unit that stores the e-mail in the storage area and the terminal. The computer functions as a transmission unit that performs processing to read the read e-mail from the storage area and transmit the read e-mail to the terminal, and the storage processing unit stores the specific data included in the received e-mail. Is included in another e-mail already stored in the e-mail, the specific data is rewritten with the specific data reference information, and the re-written e-mail is stored in the storage area. When the specific data reference information is included in the e-mail read from the storage area, the specific data reference information is written back to the specific data and written back. The present invention relates to a program for performing processing for transmitting an electronic mail to the terminal.

  The present invention also relates to an information storage medium storing the above program and a server configured as each of the above units. In the present invention, when the specific data included in the received e-mail is included in another e-mail already stored in the storage area, the specific data is rewritten with the specific data reference information, and the rewritten e-mail is Since the process of storing in the storage area is performed, the capacity for using the storage area can be saved more than in the past. In the present invention, when specific data reference information is included in the e-mail read from the storage area, the specific data reference information is rewritten to the specific data, and the rewritten e-mail is transmitted to the terminal. Thus, the original e-mail content can be transmitted without being lost.

  (2) Further, in the program of the present invention, the storage processing unit uses the attached file data included in the received electronic mail as the specific data, and the attached file data is stored in the other storage area already stored in the storage area. If it is the same as the attachment file data or the body text of the mail, the attachment file data included in the received email is rewritten with the specific data reference information, and the rewritten email is stored in the storage area. Also good.

  According to the present invention, it is possible to avoid redundantly storing the attached file data in the storage area, and it is possible to save the capacity for using the storage area as compared with the related art. According to the present invention, for example, when an e-mail attached with a large-capacity file such as audio data or image data is stored in the storage area, the amount of use of the storage area can be significantly reduced compared to the conventional case.

  (3) In the program of the present invention, when the storage processing unit includes a plurality of attached file data in the received e-mail, the attached file data is already stored in the storage area for each attached file data. If the attachment data is the same as the attachment data or body of another e-mail, and the attachment data is the same as the attachment data or body of another e-mail already stored in the storage area, the attachment The file data may be rewritten to the specific data reference information, and the rewritten electronic mail may be stored in the storage area.

  The present invention can avoid storing duplicate attachment file data in the storage area even if the email includes a plurality of attachment file data, and saves the capacity to use the storage area than before. can do.

  (4) Further, in the program of the present invention, the storage processing unit uses the text included in the received email as the specific data, and the text is the text of another email already stored in the storage area or If it is the same as the attached file data, the body included in the received e-mail may be rewritten with the specific data reference information, and the rewritten e-mail may be stored in the storage area.

  According to the present invention, it is possible to avoid storing the received body text of the received electronic mail in the storage area, and it is possible to save the capacity of using the storage area as compared with the conventional case.

  (5) Further, according to the program of the present invention, the storage area includes a mailbox of each user managed by the server and a specific area, and the storage processing unit receives an e-mail in which a plurality of destinations are designated. If received, the email reference information corresponding to the received email is stored in each user's mailbox corresponding to each destination, and one email is stored in a specific area. Based on the e-mail reference information stored in the mailbox of the user who has received the reception request, the transmitting unit reads out the e-mail from the specific area and transmits the read e-mail to the terminal. May be.

  In the present invention, when an e-mail with a plurality of destinations specified is received, e-mail reference information corresponding to the received e-mail is stored in each user's mailbox corresponding to each destination, and Since the mail is stored in the specific area, the capacity for using the storage area can be saved as compared with the conventional method.

  (6) Further, the program of the present invention includes a reference determination unit that determines whether or not an electronic mail stored in the storage area is referred to, and an electronic mail that is determined not to be referred to in the storage area. The computer may be caused to further function as a deletion unit that performs a process of deleting from the computer.

  Since the present invention performs processing for deleting e-mails that are determined not to be referenced from the storage area, it is possible to delete e-mails that do not need to be saved, and effectively use the limited storage area be able to.

An example of the mail system of this embodiment. An example of a functional block diagram of a server of this embodiment. FIG. 3A is an explanatory diagram of a conventional e-mail storage process. FIG. 3B is an explanatory diagram of the e-mail storage process of the present embodiment. Explanatory drawing of specific information. Explanatory drawing of the storing process of the conventional electronic mail. Explanatory drawing of the storage process of this embodiment. Explanatory drawing of a hash table. Explanatory drawing of the attachment file data of an electronic mail of this embodiment, and a text. Explanatory drawing of the storage process of this embodiment. Explanatory drawing of the storage process of this embodiment. Explanatory drawing of the storage process of this embodiment. Explanatory drawing of the storage process of this embodiment. Explanatory drawing of the storage process of this embodiment. Explanatory drawing of a reference value. The flowchart figure of the storage process of this embodiment. The flowchart figure of the storage process of this embodiment. The flowchart figure of the transmission processing of this embodiment.

  Hereinafter, this embodiment will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Mail System FIG. 1 is an example of a mail system according to this embodiment. The server 10 of this embodiment functions as an MTA (Mail Transfer Agent), and receives and delivers electronic mail over the network via SMTP. The server 10 also receives a request for receiving an e-mail from the terminal 20 through POP or IMAP, and performs processing for transmitting the e-mail to the terminal 20.

  The server 10 receives an electronic mail including an envelope destination (destination mail address), an envelope sender (sender mail address), and a message used for delivery processing. Then, the server 10 determines a delivery destination mail server based on the envelope destination and delivers the electronic mail received via the network to the delivery destination mail server.

  More specifically, the server 10 performs a process of receiving, via SMTP, an electronic mail transmitted from a sender such as MUA (Mail User Agent). For example, the server 10 receives an email transmitted from the terminal 20 or another mail server via SMTP. The MUA is a client program that performs processing for sending and receiving e-mail to and from the server 10 via the network, and performs processing for sending an e-mail from which the user is a sender and receiving e-mail addressed to the user. .

  Next, the server 10 has received the DNS (Domain Name System) server that manages the destination domain of the received email envelope, the DNS server in the local area of the server 10, or another DNS server. Query the destination domain of the email envelope (eg, query MX record for destination domain). Then, the electronic mail is delivered (local delivery or remote delivery) to a delivery destination mail server determined by a response message from the DNS server.

  In addition, the server 10 according to the present embodiment performs a process of transmitting an e-mail addressed to the user stored in the storage area to the terminal 20 in response to a request from the user's terminal 20 through POP or IMAP. It can be carried out.

  Further, the server 10 of the present embodiment may function as a Web server that provides a Web service. For example, the server 10 may accept an access request such as transmission of an e-mail or reception of an e-mail from a Web browser of the terminal 20 through HTTP (HyperText Transfer Protocol).

  Further, the mail system is not limited to one server 10 and may be configured by a plurality of servers 10. Further, the storage area 60 may be one or a plurality of storage devices (one or a plurality of hardware) different from the server 10.

2. Configuration FIG. 2 is an example of a functional block diagram of the server 10 of the present embodiment. Note that the server 10 according to the present embodiment does not need to include all the units illustrated in FIG. 2 and may have a configuration in which some of the units are omitted.

  The storage unit 50 serves as a work area for the processing unit 100 and the like, and its function can be realized by hardware such as a RAM (VRAM). The storage unit 50 of the present embodiment includes a storage area 60. This storage area 60 is a storage area for storing the e-mail when the domain of the destination of the received e-mail is the same as the domain of the server 10 (when the user managed by the server 10 is the destination) It is. The storage area 60 includes a mailbox 70 and a specific area 80. The server 10 is provided with a mailbox 70 for each user managed by the server 10. Mailbox 70 is a given storage area and is provided in association with each user information managed by the server. For example, the mail box 70 stores e-mail and e-mail reference information. The specific area 80 stores received e-mail and specific data. For example, the specific data is an e-mail body and attached file data.

  The storage unit 50 also stores e-mail reference information, specific data reference information, a hash table TB in which hash values are registered in association with the specific data reference information, a reference value R1 corresponding to the e-mail reference information, and specific data reference information. A corresponding reference value R2 or the like may be stored. In addition, the storage unit 50 may be provided with a spool area for temporarily storing e-mail received by the receiving unit 111 of the delivery handling unit (SMTP) for delivery (local delivery or remote delivery). . The storage unit 50 may store user information (user name, password) of the user managed by the server 10 and a user mailbox name.

  The information storage medium 180 can be read by a computer, and the information storage medium 180 stores programs, data, and the like. That is, the information storage medium 180 stores a program for causing a computer to function as each unit of the present embodiment (a program for causing a computer to execute processing of each unit). That is, the processing unit 100 can perform various processes of the present embodiment based on data read from a program (data) stored in the information storage medium 180. For example, the information recording medium 180 is an optical disk (CD, DVD), a magneto-optical disk (MO), a magnetic disk, a hard disk, a magnetic tape, a memory (ROM), a memory card, or the like.

  The processing unit 100 performs various processes of the present embodiment based on a program (data) stored in the storage unit 50. Note that the processing unit 100 of the present embodiment reads the program and data stored in the information storage medium 180, stores the read program and data in the storage unit 50, and performs processing based on the program and data. Also good. The processing unit 100 (processor) performs various processes using the main storage unit in the storage unit 50 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.) and programs.

  The processing unit 100 of this embodiment includes a delivery support unit (SMTP) 110 and a reception support unit (POP / IMAP) 120.

  The delivery handling unit 110 performs reception and delivery processing (storage processing) of electronic mail through an electronic mail delivery protocol such as SMTP. The delivery handling unit 110 includes a receiving unit 111, a storage processing unit 112, and a delivery unit 113.

  For example, the receiving unit 111 performs processing (accepting processing) for receiving an e-mail that is transmitted from the sending source and designated as an envelope destination by the MUA 21 of the terminal 20.

  Further, the storage processing unit 112, when the domain of the destination of the received email is the same as the domain managed by the server 10, that is, when the destination of the received email is a user managed by the server 10, The electronic mail is stored in the storage area 60. That is, the storage processing unit 112 performs local delivery processing for delivery to a user who has an account in the same system in which the server 10 operates. Note that the local delivery process may be performed by an MDA (Mail Delivery Agent) which is a dedicated local delivery agent. The number of domains managed by the server 10 is not limited to one and may be plural.

  In addition, when the specific data included in the received e-mail is included in another e-mail already stored in the storage area 60, the storage processing unit 112 rewrites the specific data with specific data reference information and rewrites the specific data. A process of storing the later e-mail in the storage area 60 is performed.

  In addition, the storage processing unit 112 uses the attached file data included in the received e-mail as specific data, and the attached file data is the same as the attached file data or text of another e-mail already stored in the storage area 60 In the process, the attached file data included in the received e-mail is rewritten to the specific data reference information, and the rewritten e-mail is stored in the storage area 60.

  Further, when the received e-mail includes a plurality of attached file data, the storage processing unit 112 attaches the attached file data of another e-mail in which the attached file data is already stored in the storage area 60 for each attached file data. Or if the attachment file data is the same as the attachment file data or the body of another e-mail already stored in the storage area 60, the attachment file data is rewritten to the specific data reference information. Then, a process of storing the rewritten e-mail in the storage area 60 is performed.

  Further, the storage processing unit 112 uses the text included in the received email as specific data, and when the text is the same as the text or attached file data of another email already stored in the storage area 60, the storage processing unit 112 The body included in the received e-mail is rewritten with the specific data reference information, and the rewritten e-mail is stored in the storage area 60.

  In addition, when receiving an e-mail with a plurality of destinations specified, the storage processing unit 112 stores e-mail reference information corresponding to the received e-mail in the mailbox 70 of each user corresponding to each destination. In addition, the electronic mail may be stored in the specific area 80.

  Further, when the destination domain of the received electronic mail is a domain of another mail server, the delivery unit 113 performs remote delivery processing (transfer processing, relay processing) for delivering the electronic mail to the other mail server.

  The reception handling unit 120 performs a process of transmitting an electronic mail to the terminal 20 through an electronic mail reception protocol such as POP or IMAP. The reception handling unit 120 of this embodiment includes a reception unit 121, a transmission unit 122, a reference determination unit 123, and a deletion unit 124.

  Upon receiving a reception request from the terminal 20, the reception handling unit 120 receives user information (user name, password) from the terminal 20, and performs user authentication processing based on the user information. For example, it is determined whether or not the received user name and password match the user name and password registered in advance on the server 10 side. If they match, the user authentication is permitted, and the mismatch does not allow the user authentication. Judgment. And the reception corresponding | compatible part 120 performs the process which transmits the electronic mail addressed to the user in whom user authentication was recognized to the said terminal 20. FIG.

  The accepting unit 121 performs processing for accepting an e-mail reception request from the terminal 20.

  The transmission unit 122 performs processing for transmitting the electronic mail stored in the storage area 60. For example, when the specific data reference information is included in the e-mail read from the storage area 60, the transmission unit 122 writes the specific data reference information back to the specific data, and transmits the rewritten e-mail to the terminal 20. Process. Further, the transmission unit 122 reads the electronic mail from the specific area 80 based on the electronic mail reference information stored in the mail box 70 of the user who has received the reception request, and transmits the read electronic mail to the terminal 20. I do.

  Further, the reference determination unit 123 performs a process of determining whether or not an electronic mail (at least a part of the electronic mail) stored in the storage area 60 is referenced. For example, the reference determination unit 123 performs a process of determining whether or not the email stored in the storage area 60 is referenced based on the reference value corresponding to the email reference information. Further, the reference determination unit 123 may perform a process of determining whether or not the e-mail stored in the storage area 60 is referenced based on the reference value corresponding to the specific data reference information.

  In addition, the deletion unit 124 performs processing for deleting an e-mail that is determined not to be referenced from the storage area 60. For example, the deletion unit 124 performs processing for deleting an e-mail whose reference value corresponding to the e-mail reference information is a predetermined value (for example, 0) from the storage area 60. In addition, the deletion unit 124 performs a process of deleting the specific data whose reference value corresponding to the specific data is a predetermined value (for example, 0) from the storage area 60.

  The terminal 20 is a computer, a mobile phone, a smartphone, a tablet computer, a mobile terminal, a game device, or the like, and functions as the MUA 21.

3. Description of Processing of the Present Embodiment The server 10 of the present embodiment receives an email sent from the sender, and stores the received email if the destination of the email is for a user managed by the server 10 A process of storing in the area 60 is performed. For example, when the destination domain of the received electronic mail indicates the address of the server 10 (for example, “aaa.com”), the received electronic mail is stored in the storage area 60. Then, in response to a request from the terminal 20, a process for transmitting an e-mail in the storage area 60 is performed. Hereinafter, details of the storage processing and transmission processing of the present embodiment will be described.

3.1 Description of Storage and Transmission Processing of E-mail with Multiple Destinations When a conventional server receives an e-mail with a plurality of destinations, it sends an e-mail with the same contents to each destination. The process of storing in the mailbox 70 is performed. For example, as shown in FIG. 3 (A), a server may receive a plurality of destinations (for example, userA @ aaa) from a given terminal 20 or another server via an SMTP command envelope destination (RCPT TO). .Com, userB@aaa.com) is received. Then, the server sends the destination userA @ aaa. com in the mail box 70A, and the destination userB @ aaa. The mail M1 is stored in the com mailbox 70B. That is, the process of storing the e-mail M1 in the respective mail boxes 70A and 70B of the respective destinations is performed despite the e-mail M1 having the same content. Therefore, the conventional server has a problem that the storage area is wasted.

  Therefore, the server 10 according to the present embodiment includes the mailbox 70 and the specific area 80 of each user in the storage area 60, and responds to each address when receiving an e-mail with a plurality of specified addresses. In addition, the electronic mail reference information corresponding to the received electronic mail is stored in each user's mailbox, and one electronic mail is stored in the specific area 80.

  For example, as shown in FIG. 3 (B), userA @ aaa. com, userB @ aaa. When the e-mail M1 to which the address of com is specified is received, e-mail reference information of the e-mail M1 is first determined. For example, if the reference information of the e-mail M1 is “001”, the server 10 uses userA @ aaa. com mailbox 70A, userB @ aaa. The reference information “001” of the e-mail M1 is stored in each of the com mail boxes 70B. Then, one electronic mail M <b> 1 is stored in the specific area 80. Here, the “e-mail reference information” is information indicating a reference destination of the received e-mail, and may be information that can uniquely identify the e-mail. For example, the “e-mail reference information” may be a unique number or a date and time when the e-mail is received. In the present embodiment, the size of the “e-mail reference information” is set to a predetermined size or less (for example, 16 bytes or less), which is smaller than a general e-mail size.

  Thus, the server 10 of this embodiment only records the reference information of the email M1 in the mailboxes 70A and 70B of the users A and B, and the received one email M1 in the specific area 80. Therefore, the amount of use of the storage area 60 can be saved as compared with the conventional case.

  For example, if the “size of the electronic mail M1” is 20,000,000 bytes and the “size of the reference information of the electronic mail M1” is 3 bytes, in the conventional server, the electronic mail M1 is individually stored in the storage area 60. It was supposed to use 40,000,000 bytes. On the other hand, the server 10 of this embodiment only needs to store one e-mail M1 and the reference information of the e-mail M1 in the storage area 60. As a result, only 20,000,006 bytes are used. As a result, the capacity for using the storage area 60 can be significantly reduced as compared with the conventional case.

  Next, a process in which the server 10 transmits an electronic mail stored in response to a reception request from the terminal 20 to the terminal 20 will be described. When the server 10 receives the reception request and the user information from the terminal 20 and accepts the user authentication, the server 10 acquires the e-mail reference information from the user's mailbox, and stores the e-mail corresponding to the acquired e-mail reference information in the specific area 80. And reading the e-mail to the terminal 20.

  For example, when receiving a reception request from the terminal 20 with the user name “userA@aaa.com”, the server 10 acquires the electronic mail reference information “001” in the mail box 70A of “userA@aaa.com”. The electronic mail M1 corresponding to the electronic mail reference information “001” is read from the specific area 80, and the read electronic mail M1 is transmitted to the terminal 20.

  The server 10 generates a transmission e-mail by adding unique information to the e-mail M1 acquired from the specific area 80 based on an e-mail standard (for example, MIME (Multipurpose Internet Mail Extensions)), The generated electronic mail may be transmitted to the terminal 20. For example, as shown in FIG. 4, a “Derived-To” header may be added to the top of the header of the email and transmitted to the terminal 20.

  Further, when the server 10 receives e-mail size request information from the terminal 20, the server 10 may transmit the e-mail size for transmission to which the unique information is added to the terminal 20. For example, as illustrated in FIG. 4, the server 10 calculates the size of the unique information, and the size of the unique information (for example, 16 bytes) to the size of the email M1 stored in the specific area 80 (for example, 1300 bytes). The total value obtained by adding (for example, 1316 bytes) may be transmitted to the terminal 20. In this way, the correct size of the e-mail for transmission can be notified to the terminal.

3.2 Example of Storage and Transmission Processing of E-mail including Attached File Data Now, as shown in FIG. 5, for example, the conventional server has a user A @ aaa. comB to the userB@aaa.com with the file F1 attached at time T3. When the e-mail M3 addressed to com is received, the e-mails M2 and M3 attached with the common file F1 are individually stored in the mail boxes 70A and 70B, so the storage area 60 is wasted. There was a problem that.

  Therefore, when the server 10 of the present embodiment receives an e-mail, the attached file data (an example of specific data) included in the received e-mail is attached file data of another e-mail already stored in the storage area 60. In the same case, the attached file data is rewritten to the specific data reference information, and the rewritten electronic mail is stored in the storage area 60. In this way, it is possible to avoid duplicate attachment file data having the same contents from being stored, and the use of the storage area 60 can be saved.

3.2.1 Example 1 of storage processing and transmission processing of e-mail including attachment file data
3.2.1.1 Storage Processing A first processing example for storing attached file data will be described. First, as shown in FIG. 6, the server 10 uses userA @ aaa. When the e-mail M2 to which the address of the com is specified is received, unique e-mail reference information indicating the reference destination of the e-mail M2 is determined. Then, if the reference information of the e-mail M2 is “002”, the server 10 determines that userA @ aaa. The reference information “002” of the e-mail M2 is stored in the mail box 70A of com.

  Next, the server 10 determines whether or not the attached file data F1 of the e-mail M2 is already stored in the specific area 80 (storage area 60 in a broad sense). That is, the server 10 determines whether or not the attached file data F1 is the same as the attached file data of another electronic mail already stored in the specific area 80. Here, the already stored other e-mails are one or a plurality of e-mails received by the server 10 in the past at a timing different from that of the e-mail M2.

  Specifically, the server 10 calculates a hash value (identification information) of the attached file data, and determines whether the attached file data of the e-mail is already stored in the specific area 80 based on the hash value. . The hash value is a value obtained based on a hash function (checksum, check digit, fingerprint, etc.). For example, an input key of a hash function is attached file data, and an output value of the hash function is a hash value. This hash value is information for identifying (specifying) attached file data (an example of specific data).

  For example, if the hash value of the attached file data F1 of the email M2 is “1549128”, the server 10 determines whether or not the hash value “1549128” is registered in the hash table TB. That is, when it is determined that the hash value “1549128” is registered in the hash table TB, the server 10 determines that the attached file data F1 of the email M2 is already stored in the specific area 80. If it is determined that the hash value “1549128” is not registered in the hash table TB, it is determined that the attached file data F1 of the e-mail M2 is not stored in the specific area 80.

  For example, if the hash value “1549128” of the attached file data F1 of the email M2 is not registered in the hash table TB at the time T2, the server 10 has the hash value “1549128” as shown in FIG. Are registered in association with the specific data reference information of the attached file data F1. Here, the “specific data reference information” is information for identifying the specific data of the reference destination, for example, information for identifying the electronic mail of the reference destination and the attached file data of the reference destination. In the present embodiment, the size of the “specific data reference information” is set to be equal to or smaller than a predetermined size, and is smaller than the general text size and the attached file data size. Specifically, “specific data reference information” is determined by a combination of “e-mail reference information (002)” and “file number (first file)”, such as “002-1.”

  The “file number” is the number of the file attached to the e-mail, and determines the number of the attached file in order from the top of the multi-part e-mail. For example, as shown in FIG. 8 (B), when the part after the second part 520 of the multipart e-mail is handled as the attachment file data, the data of the part body 522 of the second part 520 is 1 The second attachment data. Although not shown in FIG. 8, for example, when there is a third part, the data of the part body of the third part is set as the second attached file data.

  That is, since the hash value “1549128” is not registered in the hash table TB at time T2, the server 10 registers the specific data reference information “002-1” in association with the hash value “1549128” and attaches it. The electronic mail M2 including the file data F1 is stored in the specific area 80 as it is.

  Thereafter, as shown in FIG. 6, at time T3 (time after T2), the server 10 determines that userB @ aaa. Assume that an e-mail M3 with a destination of com is received. The e-mail M3 includes attached file data F1 having the same content as the file data attached to the e-mail M2.

  First, the server 10 uses userB @ aaa. The reference information of the e-mail M3 is determined and the reference information “003” is stored in the com mail box 70B. Then, the server 10 obtains the hash value of the attached file data F1 attached to the electronic mail M3, and determines whether or not the hash value is registered in the hash table TB. For example, since the hash value “1549128” of the attached file data F1 is registered in the hash table TB at time T3, the server 10 has already stored the attached file data F1 of the email M3 in the specific area 80. Judge that That is, the server 10 determines that the attached file data F1 is the same as the attached file data F1 of another electronic mail M2 already stored in the specific area 80 at time T3.

  Then, the server 10 rewrites the attached file data F1 of the e-mail M3 to the specific data reference information “002-1” corresponding to the hash value “1549128”, and stores the rewritten e-mail M3 in the specific area 80. Do.

  As described above, the server 10 according to the present embodiment can avoid storing the attached file data in the storage area 60 as a result, thereby saving the capacity for using the storage area 60 as compared with the prior art. be able to. In particular, the server 10 according to the present embodiment saves the amount of use of the storage area 60 as compared with the conventional case when storing an e-mail attached with a large-capacity file such as voice data or image data in the storage area 60. can do.

  In addition, when storing the attachment file data for the first time, the server 10 of the present embodiment does not separate the attachment file from the e-mail, and therefore rewrites the attachment file data with the minimum necessary amount. As a result, the processing load can be reduced.

  When the server 10 determines that the received e-mail includes a plurality of attached file data, the attached file data is already stored in the specific area 80 (storage area 60 in a broad sense) for each attached file data. If the attached file data is the same as the attached file data of another e-mail already stored in the specific area 80, the attached file data is specified. The data reference information may be rewritten, and the rewritten electronic mail may be stored in the specific area 80.

  For example, as shown in FIG. 9, at time T4, userA @ aaa. com@address.com is received, userA @ aaa. The reference information “004” of the e-mail M4 is stored in the mail box 70A of com. Then, the server 10 determines whether or not the attached file data F2 and F3 of the e-mail M4 is already stored in the specific area 80.

  For example, since the hash value “3478204” of the attached file data F2 of the email M4 is not registered in the hash table TB at the time T4, the server 10 uses the hash value “3478204” as the specific data reference information “004-1”. "In association with". " The specific data reference information “004-1” means the first file of the electronic mail M4 (reference information 004). Further, since the hash value “3478232” of the attached file data F3 of the email M4 is not registered in the hash table TB at the time point T4, the server 10 uses the hash value “3478232” as the specific data reference information “004-2”. "In association with". " The specific data reference information “004-2” means the second file of the electronic mail M4 (reference information 004). Then, the server 10 performs processing for storing the e-mail M4 including the attached file data F2 and the attached file data F3 in the specific area 80 as it is.

  Thereafter, at time T5 (time after T4), the server 10 determines that userB @ aaa. Assume that an e-mail M5 with a destination of com is received. The e-mail M5 includes attached file data F3 and attached file data F4.

  First, the server 10 uses userB @ aaa. The reference information “005” of the e-mail M5 is stored in the com mail box 70B. Then, the server 10 determines whether or not the attached file data F3 and F4 of the email M5 is already stored in the specific area 80.

  For example, since the server 10 determines that the hash value “3478204” of the attachment file data F3 of the email M5 is registered in the hash table TB at the time T5, the server 10 uses the hash value of the attachment file data F3 of the email M5. The specific data reference information “004-2” corresponding to “3478204” is rewritten. Further, since the hash value “2349872” of the attached file data F4 of the email M5 is not registered in the hash table TB at the time point T5, the server 10 sets the hash value “2349872” in the hash table TB to the specific data reference information “ "005-2". The specific data reference information “005-2” means the second file of the e-mail M5 (reference information 005). Then, the server 10 performs processing for storing, in the specific area 80, the e-mail M5 in which the attached file data F3 is rewritten to the specific data reference information “004-2”.

3.2.1.2 Transmission Process Next, the transmission process of the server 10 will be described. First, when the server 10 receives a reception request and user information from the terminal 20 and accepts user authentication, the server 10 acquires e-mail reference information from the user's mailbox. Then, based on the acquired e-mail reference information, the e-mail is read from the specific area 80, and when the e-mail read from the specific area 80 includes the specific data reference information, the specific data reference information is A process of writing back the attached file data and transmitting the written back e-mail to the terminal 20 is performed. On the other hand, when the specific data reference information is not included in the e-mail read from the specific area 80, a process of transmitting the read e-mail to the terminal 20 is performed. In this way, an e-mail addressed to the user can be transmitted to the terminal as in the conventional case.

  For example, after T3 in FIG. 6, when the server 10 receives a reception request from the terminal 20 with the user name “userB@aaa.com”, the e-mail reference information “in the mailbox 70B of“ userB@aaa.com ”“ 003 "is acquired. Then, the e-mail M3 corresponding to “003” is read from the specific area 80.

  Then, the server 10 determines whether or not the specific data reference information is included in the email M3. For example, when the specific data reference information registered in the hash table TB is detected in the email M3, the server 10 determines that the specific data reference information is included in the email M3. On the other hand, if the server 10 does not detect the specific data reference information registered in the hash table TB in the email M3, the server 10 determines that the email M3 does not include the specific data reference information.

  For example, when determining that the e-mail M3 includes the specific data reference information, the server 10 acquires the specific data reference information “002-1”. Then, the attached file data F1 corresponding to the specific data reference information “002-1” is acquired, and the specific data reference information “002-1” of the email M3 is written back to the file data F1. For example, the specific data reference information “002-1” means the first attached file of the e-mail M2, so the server 10 uses the first attached file data F1 (for example, the second part of the e-mail M2). (Part body) is read, the specific data reference information “002-1” is deleted, and the file data F1 is written instead. Then, the server 10 performs a process of transmitting the rewritten electronic mail M3 to the terminal 20. As described above, the server 10 may generate e-mail M3 for transmission by adding unique information to the e-mail M3 and transmit it to the terminal 20. Further, when the server 10 receives e-mail size request information from the terminal 20, the server 10 may transmit the e-mail size for transmission to which the unique information is added to the terminal 20.

  In addition, when the server 10 acquires a plurality of pieces of email reference information in the mailbox of the user who has received the reception request, the server 10 performs processing for each piece of email reference information. Further, when the read e-mail includes a plurality of specific data reference information, the server 10 writes back and writes back each of the plurality of specific data reference information to the file data corresponding to the specific data reference information. The process of transmitting the received e-mail to the terminal 20 is performed.

  As described above, the server 10 according to the present embodiment can restore the original attached file data even if a part of the e-mail is rewritten to the specific data reference information. You can send an email.

3.2.2 Example 2 of storage processing and transmission processing of e-mail including attached file data
3.2.2.1 Storage Processing Further, as shown in FIG. 10, the server 10 according to the present embodiment rewrites the attached file data of the received e-mail to the specific data reference information, and rewrites the e-mail after rewriting. You may make it store in the specific area | region 80. FIG.

  Then, the server 10 determines whether or not the attached file data of the e-mail is already stored in the specific area 80 based on the hash value of the attached file data, and the attached file data is not stored in the specific area 80. In this case, the attached file data is stored in the specific area 80. On the other hand, when the attached file data is stored in the specific area 80, control is performed so that the attached file data is not stored redundantly in the specific area 80.

  For example, as illustrated in FIG. 10, when the attached file data F1 of the e-mail M2 is not stored in the specific area 80 at time T2, the server 10 sets the hash value “1549128” of F1 to the specific data of F1. Registration is made in association with the reference information “002-1.” The attached file data F1 of the e-mail M2 is rewritten to the specific data reference information “002-1”, and the rewritten e-mail M2 is stored in the specific area 80. The actual data of the attached file data F1 is also stored in the specific area 80. Process to store in.

  After that, when the server 10 receives the e-mail M3 received at time T3, the attached file data F1 is stored in the specific area 80. Therefore, the attached file data F1 is stored in the specific data reference information “002-1.” Rewriting and storing the rewritten e-mail M3 in the specific area 80 are performed. Note that since the hash value “1549128” of the attached file data F1 has already been registered in the hash table TB at time T3, control is performed so that the attached file data F1 is not stored in the specific area 80 at time T3.

  Note that the server 10 performs processing for each attached file data when it is determined that the server 10 includes a plurality of attached file data, as in the above-described “3.2.1.1 storage process”. Also good.

  As described above, also in the processing example 2, the server 10 can save the capacity to use the storage area 60 as compared with the conventional case by controlling so that the same attached file data is not stored redundantly.

3.2.2.2 Transmission Process Next, the transmission process of the server 10 will be described. Also in Example 2, the server 10 basically performs the same process as “3.2.1.2 Transmission Process” in Example 1.

  For example, the server 10 determines whether or not the read e-mail includes the specific data reference information. If the read e-mail includes the specific data reference information, the specific data reference information is specified. A process of writing back the attached file data (attached file data corresponding to the specific data reference information) stored in the area 80 and transmitting the written back e-mail to the terminal 20 is performed. On the other hand, when the specific data reference information is not included in the e-mail read from the specific area 80, a process of transmitting the read e-mail to the terminal 20 is performed.

3.2.3 Example 3 for storing and sending e-mail including attached file data
3.2.3.1 Storage Processing Further, as shown in FIG. 11, the server 10 of the present embodiment rewrites the attached file data of the received e-mail with the specific data reference information, It may be stored in the destination mailbox 70.

  Then, the server 10 determines whether or not the attached file data of the e-mail is already stored in the specific area 80 based on the hash value of the attached file data, and the attached file data is not stored in the specific area 80. In this case, the attached file data is stored in the specific area 80. On the other hand, when the attached file data is stored in the specific area 80, control is performed so that the attached file data is not stored redundantly in the specific area 80.

  For example, as shown in FIG. 11, at time T2, when the attached file data F1 of the email M2 is not stored in the specific area 80, the server 10 uses the attached file data F1 as the specific data reference information “002-1”. And the process of storing the rewritten electronic mail M2 in the mail box 70A and the process of storing the attached file data F1 in the specific area 80. Also, the server 10 registers the specific data reference information “002-1” of F1 in the hash table TB in association with the hash value “1549128” of F1.

  Thereafter, when the server 10 receives the e-mail M3 received at time T3, the attached file data F1 of the e-mail M3 is rewritten with the specific data reference information “002-1”, and the rewritten e-mail M3 is stored in the mail box 70B. Process to store. Note that since the hash value “1549128” of the attached file data F1 has already been registered in the hash table TB at time T3, control is performed so that the attached file data F1 is not stored in the specific area 80 at time T3.

  If the server 10 determines that the received electronic mail includes a plurality of attached file data, the server 10 may perform processing for each attached file data. For example, the server 10 rewrites the attached file data with the specific data reference information for each attached file data, and stores the rewritten e-mail in the mailbox 80 of each destination. Further, the server 10 determines, for each attachment file data, whether the attachment file data of the e-mail is already stored in the specific area 80 based on the hash value of the attachment file data, and the attachment file data is stored in the specific area. If the file is not stored in 80, the attached file data is stored in the specific area 80.

  As described above, also in Example 3, the server 10 can save the capacity to use the storage area 60 as compared with the conventional case by controlling so that the same attached file data is not stored redundantly.

3.2.3.2 Transmission Process Next, the transmission process of the server 10 in Process Example 3 will be described. When the server 10 receives the reception request and the user information from the terminal 20 and accepts the user authentication, the server 10 reads the e-mail from the user's mailbox.

  Then, the server 10 determines whether or not the read e-mail includes the specific data reference information. If the read e-mail includes the specific data reference information, the specific data reference information is A process of writing back the attached file data (attached file data corresponding to the specific data reference information) stored in the specific area 80 and transmitting the rewritten e-mail to the terminal 20 is performed. On the other hand, when the specific data reference information is not included in the e-mail read from the specific area 80, a process of transmitting the read e-mail to the terminal 20 is performed.

  Further, when the read e-mail includes a plurality of specific data reference information, the server 10 writes back the specific data reference information to the corresponding file data for each of the plurality of specific data reference information. A process of sending an e-mail to the terminal 20 is performed. In addition, when there are a plurality of e-mails in the user's mailbox, the server 10 performs processing for each e-mail. As described above, the server 10 may generate e-mail for transmission by adding unique information and transmit it to the terminal 20. Further, when the server 10 receives e-mail size request information from the terminal 20, the server 10 may transmit the e-mail size for transmission to which the unique information is added to the terminal 20.

3.2.4 Description of Text and Attached File Data FIG. 8A shows an example of single-part format e-mail. As shown in FIG. 8A, a single-part e-mail is processed on the assumption that there is no attached file. Note that the single-part e-mail is composed of a header 200 and a body 300 made up of a single part, and performs a process of extracting the body 300 based on blank line information.

  FIG. 8B shows an example of multi-part electronic mail. As shown in FIG. 8B, a multi-part electronic mail is composed of a header 400 and a plurality of parts 510 and 520.

  The attached file data in the present embodiment refers to attached file data among e-mail data, and is part data of a MIME standard multipart format (for example, part body data or part header and part data). Body data). Normally, the first part of the multipart e-mail contains a message recorded as the body text in the mail software by the user. Therefore, in this embodiment, the data of the first part 510 (part body 512) Data or data of part header 511 and part body 512) is processed as text, and data of second part 520 (data of part body 522 or data of part header 521 and part body 522) is processed as attachment file data. I do. If there are three or more parts, the data of each part after the second is processed as each attached file data. That is, when there are three or more parts, a plurality of attached file data are included.

  Note that there is an electronic mail in which any part of the multipart format is recorded with data in the multipart format. In such a case, the data of each part may be processed recursively as attached file data. Also, control is performed so that the data of the lower multipart part (nested multipart part data) recorded in the multipart format part is not processed as attachment file data. The data of each part may be processed as attached file data.

  The server 10 refers to the part header of each part, and when the “Content-Type” of the part header is specific header information such as “image / jpeg”, the data of the part is handled as attached file data. You may do it.

  Further, the server 10 may handle each piece of data as each attached file data in a multi-part electronic mail as shown in FIG. That is, in the case of FIG. 8B, the data of the first part 510 of the electronic mail may be handled as the first attached file data, and the data of the second part 520 may be handled as the second attached file data. Good. Note that the server 10 may process the data 500 of all the parts as a text or may not process the text in the multi-part electronic mail as shown in FIG. 8B.

  The server 10 determines that the e-mail has attached file data when the “Content-Type” of the e-mail header is “multipart / mixed” (determines that the e-mail is a multi-part format e-mail). To do). At that time, the server 10 acquires data indicated by the delimiter information (boundary) of each part, and extracts each part data based on the delimiter information. Further, the server 10 performs a process of extracting the part header and part body data of each part based on the blank line information, reading the attached file data, extracting the attached file data, and rewriting the specific data reference information. .

3.3 Example of Email Storage Processing and Transmission Processing Related to Text The server 10 determines that the received email text (an example of specific data) is the same as the text of other emails already stored in the storage area 60. In addition, the body of the received e-mail may be rewritten with the specific data reference information, and the rewritten e-mail may be stored in the storage area 60.

3.3.1 Example 1 of storing and sending e-mail related to text
3.3.1.1 Storage Processing For example, as illustrated in FIG. 12, the server 10 determines that userA @ aaa. When the e-mail M6 to which the address of com is specified is received, the e-mail reference information of the e-mail M6 is determined. For example, if the electronic mail reference information of the electronic mail M6 is “006”, userA @ aaa. The electronic mail reference information “006” is stored in the mail box 70A of com.

  Next, at time T6, the server 10 obtains the hash value of the body B1 of the email M6, and based on the hash value, the body B1 of the email M6 is already stored in the specific area 80 (storage area 60 in a broad sense). It is judged whether it is done. This hash value is information for identifying (specifying) the text (an example of specific data). That is, the server 10 determines whether or not the hash value is registered in the hash table TB.

  For example, if the hash value of the text B1 is “3451432,” it is determined whether this hash value “3451432” is registered in the hash table TB. When the hash value “3454132” of the text B1 is not registered in the hash table TB, the server 10 determines that the text of the email M6 is not stored in the specific area 80, and hashes the hash value in the hash table TB. The specific data reference information “006-B” is registered in association with the value “3451432”. The specific data reference information “006-B” is information obtained by combining the reference information “006” of the e-mail M6 and the data “B” indicating that the reference destination data is the text. Then, the server 10 performs processing for storing the e-mail M6 in the specific area 80 as it is.

  Thereafter, at time T7 (timing after time T6), the server 10 determines userB @ aaa. Assume that an e-mail M7 in which the address of com is specified is received. Server 10 uses userB @ aaa. The electronic mail reference information “007” of the electronic mail M7 is stored in the mail box 70B of com.

  And the server 10 calculates | requires the hash value of the text B1 of the email M7. Then, the server 10 determines whether or not the hash value of the email M7 is registered in the hash table TB at time T7. For example, if the hash value “3451432” of the body B1 of the email M7 is registered in the hash table TB at the time T7, the server 10 determines that the body of the email M7 is stored in the specific area 80. . Then, the body of the e-mail M7 is rewritten with the specific data reference information “006-B” corresponding to the hash value “3451432”, and the e-mail M7 is stored in the specific area 80.

3.3.1.2 Transmission Process Next, the transmission process of the server 10 will be described. The server 10 receives the reception request and user information from the terminal 20, and reads the e-mail from the user mailbox when the user authentication is accepted.

  Then, the server 10 determines whether or not the read e-mail includes the specific data reference information. If the read e-mail includes the specific data reference information, the server 10 displays the specific data reference information in the specific area. A process of writing back the text stored in 80 (text corresponding to the specific data reference information) and transmitting the written back e-mail to the terminal 20 is performed. On the other hand, when the specific data reference information is not included in the e-mail read from the specific area 80, a process of transmitting the read e-mail to the terminal 20 is performed. In this way, an e-mail addressed to the user can be transmitted to the terminal as in the conventional case.

  For example, when the server 10 receives a reception request from the terminal 20 with the user name “userB@aaa.com” after T7 in FIG. 12, the e-mail reference information “in the mailbox 70B of“ userB@aaa.com ”“ 007 "is acquired. Then, the electronic mail M7 corresponding to “007” is read from the specific area 80.

  Then, the server 10 determines whether or not the specific data reference information is included in the email M7. For example, when it is determined that the e-mail M7 includes the specific data reference information, the server 10 acquires the specific data reference information “006-B”, acquires the text B1 corresponding to “006-B”, and The specific data reference information “006-B” is written back to the text B1. For example, since the specific data reference information “006-B” means the text of the email M6, the server 10 reads the text B1 of the email M6, and the specific data reference information “006-B” of the email M7. Is deleted and the text B1 is written instead. Then, the server 10 performs a process of transmitting the rewritten electronic mail M7 to the terminal 20. As described above, the server 10 may generate e-mail M7 for transmission by adding unique information to the e-mail M7 and transmit it to the terminal 20. Further, when the server 10 receives the request information of the size of the electronic mail M7 from the terminal 20, the server 10 may transmit the size of the electronic mail M7 for transmission to which the unique information is added to the terminal 20.

  In addition, when the server 10 acquires a plurality of pieces of email reference information in the mailbox of the user who has received the reception request, the server 10 performs processing for each piece of email reference information. In addition, when the read electronic mail includes a plurality of specific data reference information, the server 10 writes back the specific data reference information in the corresponding text for each of the plurality of specific data reference information, A process of transmitting mail to the terminal 20 is performed.

  As described above, the server 10 according to the present embodiment can restore the original attachment file data even if the text of a part of the e-mail is rewritten with the specific data reference information, so that the data can be reliably lost. Email can be sent to.

3.3.2 Example 2 for storing and sending e-mail related to the text
3.3.2.1 Storage Processing Further, as shown in FIG. 13, the server 10 rewrites the text of the received e-mail with the specific data reference information, and the rewritten e-mail is stored in the mail box 70 of each destination. You may make it store.

  Then, the server 10 determines whether or not the body of the e-mail is already stored in the specific area 80 based on the hash value of the body, and specifies the body when the body is not stored in the specific area 80. Store in area 80. On the other hand, when the text is stored in the specific area 80, control is performed so that the text is not duplicated and stored in the specific area 80.

  For example, as shown in FIG. 13, at time T6, the server 10 rewrites the text B1 of the email M6 with the specific data reference information “006-B”, and stores the rewritten email M6 in the mailbox 70A. I do. Then, when the text B1 is not stored in the specific area 80, the server 10 performs a process of storing the text B1 in the specific area 80, and associates the hash value “3454132” of the text B1 with the hash table TB. The specific data reference information “006-B” of the text B1 is registered.

  Thereafter, when the server 10 receives the e-mail M7 received at time T7, the body B1 of the e-mail M7 is rewritten with the specific data reference information “006-B”, and the rewritten e-mail M7 is stored in the mail box 70B. Process. Note that since the hash value “3454142” of the text B1 is already registered in the hash table TB at the time T7, control is performed so that the text B1 is not stored in the specific area 80 at the time T7. As described above, also in Example 2, the server 10 can save the capacity to use the storage area 60 as compared with the conventional case by controlling not to duplicately store the same text.

3.3.2.2 Transmission Process Next, the transmission process of the server 10 will be described. The server 10 receives the reception request and user information from the terminal 20, and reads the e-mail from the user mailbox when the user authentication is accepted.

  Then, the server 10 rewrites the read specific data reference information of the e-mail into the text stored in the specific area 80 (the text corresponding to the specific data reference information), and writes the rewritten e-mail to the terminal The process which transmits to 20 is performed. In addition, when there are a plurality of e-mails in the user's mailbox, the server 10 performs processing for each e-mail.

3.3.3 Other When the attached file data of the received e-mail is the same as the text of another e-mail already stored in the storage area 60 (for example, the specific area 80), the server 10 receives the received e-mail. The attached file data of the mail may be rewritten with the specific data reference information, and the rewritten electronic mail may be stored in the storage area 60.

  Further, the server 10 determines that the received body text of the received e-mail is the same as the attached file data of another e-mail already stored in the storage area 60 (for example, the specific area 80). May be rewritten with the specific data reference information, and the rewritten electronic mail may be stored in the storage area 60.

  For example, when the server 10 receives a multipart e-mail, the specific data is already stored in the storage area 60 (for example, the specific area 80) for each specific data (for each of the text and each attached file data). It is determined whether or not it is the same as the specific data (attached file data or text) of the other electronic mail that has been sent. If the specific data is the same as the specific data of another electronic mail already stored, the specific data of the received electronic mail is rewritten with specific data reference information, and the rewritten electronic mail is stored in the storage area 60. You may make it store.

4). Deletion Processing The server 10 of this embodiment may be controlled not to delete the data stored in the storage area 60, or may delete the data stored in the storage area 60 under a predetermined condition. Good.

4.1 Method for Deleting Email Based on Reference Value Corresponding to Email Reference Information For example, when the server 10 deletes an email stored in the storage area 60 under a predetermined condition, A reference value is set in association with the mail reference information, and data deletion processing is performed with reference to the reference value, so that necessary data is not accidentally deleted.

4.1.1 Processing for Setting Reference Value FIG. 14A shows an example of a reference value R1 corresponding to e-mail reference information. For example, the reference value R1 corresponding to one e-mail corresponds to the number by which a part or all of the e-mail is referred. For example, when the R1 value is “0”, it indicates a state that is not referred to, and when the R1 value is “1” or more, it indicates a state that is referenced by one or more e-mails.

  First, the server 10 sets the R1 value according to the number of destinations. For example, as shown in FIG. 3, when two destinations are designated in the e-mail reference information “001”, the R1 value of the e-mail reference information “001” is set to “2”. Further, as shown in FIG. 6, when one destination is designated for the email “002”, the R1 value of the email reference information “002” is set to “1”. That is, the server 10 sets the R1 value of the e-mail reference information to be equal to or greater than the number of e-mail destinations.

  In addition, when specific data (body text or attached file data) that is the whole or part of the body of an e-mail is referenced from another e-mail, the R1 value of the referenced e-mail is determined according to the number of references. increase. For example, the R1 value corresponding to the specific data reference information is increased by 1 (incremented) according to the number of rewrites to the specific data reference information.

  Specifically, as shown in FIG. 6, when the attached file data F1 of the e-mail M3 is rewritten to the specific data reference information “002-1,” the R1 value corresponding to the e-mail reference information “002” is increased by 1. Let Also, as shown in FIG. 12, when the text of the email M7 is rewritten with the specific data reference information “006-B”, the R1 value of the email reference information “006” is incremented by one. The same processing is performed for the examples shown in FIGS.

4.1.2 E-mail Deletion Process Based on Reference Value The server 10 according to the present embodiment corresponds to e-mail reference information after the e-mail transmission process corresponding to the e-mail reference information to the terminal 20 is normally completed. A process of decrementing (decrementing) the R1 value by “1” is performed. When the specific data reference information is included in the e-mail, each time the specific data reference information is written back into the text or attached file data, the R1 value of the reference e-mail is decreased by 1 (decremented).

  For example, after the time T1 in FIG. 3, the server 10 has a user A @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 sends userA @ aaa. After normally completing the transmission process of the email M1 corresponding to the email reference information “001” from the terminal 20 of com, the R1 value corresponding to the email reference information “001” is decreased by “1”. That is, the R1 value corresponding to the e-mail reference information “001” is updated from “2” to “1”.

  Thereafter, the server 10 determines that userB @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 uses userB @ aaa. After normally completing the transmission process of the email M1 corresponding to the email reference information “001” from the terminal 20 of com, the R1 value corresponding to the email reference information “001” is decreased by “1”. For example, the R1 value corresponding to the electronic mail reference information “001” is updated from “1” to “0”.

  Further, after time T3 in FIG. 6, the server 10 is in a state where the R1 value corresponding to the email reference information “002” is “2” and the R1 value corresponding to the email reference information “003” is “1”. , UserA @ aaa. Suppose that a reception request is received from the terminal 20 of com.

  Then, the server 10 sends userA @ aaa. After the transmission processing of the e-mail M2 corresponding to the e-mail reference information “002” from the terminal 20 of the com ends normally, the R1 value corresponding to the e-mail reference information “002” is decreased by “1”. That is, the R1 value corresponding to the electronic mail reference information “002” is updated from “2” to “1”.

  Thereafter, the server 10 determines that userB @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 uses userB @ aaa. The specific data reference information “002-1” of the e-mail M3 corresponding to the e-mail reference information “003” is written back to the original specific data (attached file data F1) from the terminal 20 of com, and the transmission process of the e-mail M3 After normal termination, the R1 value corresponding to the e-mail reference information “003” is decreased by “1”. That is, the R1 value corresponding to “003” is updated from “1” to “0”. Further, based on the specific data reference information “002-1”, the R1 value corresponding to the reference destination electronic mail reference information “002” is decreased by “1”. That is, the R1 value corresponding to the e-mail reference information “002” is updated from “1” to “0”. Note that the same processing is performed for the examples of FIGS.

  Then, the server 10 finally regards the email corresponding to the email reference information whose R1 value is 0 as an email that has not been referenced, and regards the email as a specific area 80 (storage area 60 in a broad sense). ) Is deleted. For example, in the example of FIG. 3, when the R1 value of the e-mail reference information “001” becomes 0, the e-mail M1 stored in the specific area 80 is deleted. Further, in the example of FIG. 6, when the R1 value of the email reference information “002” becomes 0, a process of deleting the email M2 stored in the specific area 80 is performed. Note that the same processing is performed for the examples of FIGS.

  Each time the server 10 updates the R1 value, the server 10 determines whether or not the R1 value has become 0. When the server 10 determines that the R1 value has become 0, the server 10 deletes the e-mail from the specific area 80. Alternatively, an e-mail whose R1 value of the e-mail reference information is 0 may be deleted at a specific deletion timing (for example, every day at 2 am). Note that the server 10 may perform control so as not to decrease the R1 value when request information for saving an e-mail is received from the terminal 20 on the server 10 side.

  As described above, the server 10 according to the present embodiment can delete e-mails that do not need to be saved. Therefore, the use of the storage area 60 can be reduced and the storage area 60 can be used effectively. . In addition, since the server 10 performs the deletion process based on the reference value, it is possible to determine the deletion process while reducing the processing load.

4.2 Method for Deleting Data Based on Reference Value Corresponding to Specific Data Reference Information The server 10 of the present embodiment sets a reference value R2 value corresponding to specific data reference information, and specifies specific data (attached file data, It is also possible to perform deletion processing of (text). For example, in the processing examples of FIGS. 11 and 13, data is deleted based on the reference value corresponding to the specific data reference information.

4.2.1 Processing for Setting Reference Value FIG. 14B shows an example of a reference value R2 corresponding to specific data reference information. For example, the reference value R2 corresponds to the number referring to the specific data. For example, when the R2 value is “0”, it indicates a state that is not referred to, and when the R2 value is “1” or more, it indicates a state that is referenced by one or more e-mails.

  For example, each time the server 10 rewrites the attached file data or the text to the specific data reference information, the server 10 increases (increments) the R2 value by one. Specifically, as illustrated in FIG. 11, when the attached file data is rewritten to the specific data reference information “002-1”, R2 corresponding to the specific data reference information “002-1” is incremented by one. Further, as shown in FIG. 13, when rewriting the text of the electronic mail R7 to the specific data reference information “006-B”, R2 corresponding to “006-B” is incremented by one.

4.2.2 Specific Data Deletion Processing Based on Reference Value The server 10 according to the present embodiment specifies a specific request after receiving a reception request from the terminal 20 and successfully completing transmission processing of an email corresponding to email reference information. A process of decrementing (decrementing) the R2 value corresponding to the data reference information by “1” is performed.

  For example, after time T3 in FIG. 11, the server 10 is in a state where the R2 value corresponding to the specific data reference information “002-1” is “2”, and userA @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 sends userA @ aaa. The specific data reference information “002-1” of the e-mail M2 in the com mailbox is written back to the attached file data F1, and after the transmission processing of the e-mail M2 is normally completed, the specific data reference information “002-1” is supported. R2 value to be reduced is decreased by “1”. That is, the R2 value corresponding to the specific data reference information “002-1” is updated from “2” to “1”.

  Thereafter, the server 10 determines that userB @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 uses userB @ aaa. The specific data reference information “002-1” of the electronic mail M3 in the com mailbox is written back to the attached file data F1, and the transmission processing of the electronic mail M3 is normally completed. R2 value to be reduced is decreased by “1”. That is, the R2 value corresponding to the specific data reference information “002-1” is updated from “1” to “0”.

  Further, after time T7 in FIG. 13, the server 10 is in a state where the R2 value corresponding to the specific data reference information “006-B” is “2”, userA @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 sends userA @ aaa. The specific data reference information “006-B” of the e-mail M6 in the mail box of com is written back to the text B1 and the transmission processing of the e-mail M6 is normally completed, and then the specific data reference information “006-B” is handled. Decrease R2 value by "1". That is, the R2 value corresponding to the specific data reference information “006-B” is updated from “2” to “1”.

  Thereafter, the server 10 determines that userB @ aaa. Suppose that a reception request is received from the terminal 20 of com. Then, the server 10 uses userB @ aaa. The specific data reference information “006-B” of the electronic mail M7 in the mail box of com is written back to the text B1 and the transmission processing of the electronic mail M7 is normally completed, and then the specific data reference information “006-B” is handled. Decrease R2 value by "1". That is, the R2 value corresponding to the specific data reference information “006-B” is updated from “1” to “0”.

  Then, the server 10 finally regards the specific data (text or attached file data) corresponding to the specific data reference information whose R2 value is 0 as the unreferenced specific data, and regards the specific data as the specific area 80. A process of deleting from the storage area 60 (in a broad sense) is performed. For example, in the example of FIG. 11, when the R2 value of the specific data reference information “002-1” becomes 0, the process of deleting the attached file data F1 stored in the specific area 80 is performed. Further, in the example of FIG. 13, when the R2 value of the specific data reference information “006-B” becomes 0, a process of deleting the text B1 stored in the specific area 80 is performed.

  Note that the server 10 determines whether or not the R2 value has become 0 each time the R2 value is updated, as in the e-mail deletion process based on the R1 value, and determines that the R2 value has become 0. In such a case, the e-mail may be deleted from the specific area 80, or the e-mail whose R2 value of the specific data reference information is 0 is deleted at a specific deletion timing (for example, every day at 2 am). It may be. Note that the server 10 may perform control so as not to decrease the R2 value when the request information for saving the e-mail is received from the terminal 20 to the server 10 side.

  As described above, the server 10 according to the present embodiment can delete specific data (body text or attached file data) that does not need to be saved, so that wasteful use of the storage area 60 is reduced, and the storage area 60 is saved. It can be used effectively. In addition, since the server 10 performs the deletion process based on the reference value, it is possible to determine the deletion process while reducing the processing load.

4.3 Others When the electronic mail is deleted, the server 10 may delete the reference information and the reference value R1 of the electronic mail. Further, when the specific data is deleted, the server 10 deletes the reference information and the reference value R2 of the specific data, and deletes the reference information and the hash value of the specific data from the hash table TB. Also good. Moreover, the said deletion process is an example and the server 10 may be made to perform the deletion process of an email or specific data in various aspects.

5. Flowchart 5.1 Storage Process Flow When the server 10 receives an e-mail addressed to a user managed by the server 10, an example of a process for storing the e-mail in the storage area 60 is shown in FIGS. 15A and 15B. It will be explained using. Note that the initial value of the R1 value is “0”. The following processing flow is an example of processing in which the attached file data is specified data, and the attached file data is rewritten and stored with specific data reference information.

First, processing for determining reference information of the received electronic mail is performed (step S10). Then, it is determined whether or not the e-mail has attached file data (step S11). If the e-mail does not have attached file data (N in step S11), the received e-mail is stored in the specific area 80 (step S12). Next, the e-mail reference information is stored in each destination mailbox (step S13). Then, the R1 value corresponding to the e-mail reference information is incremented by the number of destinations (step S14).

  On the other hand, when the e-mail has attached file data (Y in step S11), processing for determining specific data reference information corresponding to the attached file is performed (step S15). Then, the hash value of the attached file data is obtained (step S16). Next, it is determined whether or not the hash value has been registered in the hash table (step S17).

  If the hash value is already registered in the hash table (Y in step S17), it is determined whether or not the attached file data actually exists (step S18). If the attached file data does not actually exist (N in step S18), the process proceeds to step S24.

  If the attached file data actually exists (Y in step S18), the electronic mail reference information is stored in each destination mailbox (step S19). Then, the attached file data of the e-mail is rewritten to the specific data reference information and stored in the specific area (step S20). Then, the R1 value corresponding to the e-mail reference information of the received e-mail is incremented by the number of destinations (step S21). Then, the R1 value corresponding to the e-mail reference information of the reference destination e-mail is incremented by the number of destinations (step S22).

  On the other hand, if the hash value has not been registered in the hash table (N in step S17), the hash value in the hash table is registered in association with the specific data reference information (step S23). Then, the attached file data is stored in the specific area (step S24). Then, the e-mail reference information is stored in each destination mailbox (step S25). Then, the electronic mail is stored in the specific area (step S26). Then, the R1 value corresponding to the email reference information of the received email is incremented by the number of destinations (step S27). The process ends here.

5.2 Flow of Transmission Process Next, an example of a process in which the server 10 transmits an e-mail to the terminal 20 in response to a reception request from the terminal 20 will be described with reference to FIG. First, when there is a reception request from the terminal 20 (Y in Step S30) and user authentication is approved (Y in Step S31), the electronic mail reference information is acquired from the user's mailbox ( Step S32). Then, an e-mail corresponding to the e-mail reference information is acquired from the specific area (step S33). Then, it is determined whether or not the specific data reference information is included in the e-mail (step S34).

  If the specific data reference information is not included in the e-mail (N in step S34), the e-mail is generated by adding unique information to the e-mail (step S35). And the process which transmits the produced | generated electronic mail to the terminal 20 which requested | required is performed (step S36). Then, the R1 value of the sent electronic mail is decremented (step S37).

  On the other hand, when the specific data reference information is included in the e-mail (Y in step S34), the specific data reference information is written back to the attached file data (step S38). Then, unique information is added to the e-mail to generate an e-mail for transmission (step S39). And the process which transmits the produced | generated electronic mail to the terminal 20 which requested | required is performed (step S40). Then, the R1 value of the transmitted email is decremented (step S41). Then, a process of decrementing the R1 value of the reference source email is performed (step S42). The process ends here.

6). In the case of managing a plurality of domains The example in which the server 10 of this embodiment manages one domain (for example, “aaa.com”) has been described. However, the server 10 has a plurality of domains (for example, “aaa.com”). , “Bbb.co.jp”) may be managed.

  For example, the server 10 may provide separate storage areas for each of a plurality of domains, and may perform an e-mail storage process and a transmission process. More specifically, the server 10 includes a storage area 60-1 for “aaa.com” and a storage area 60-2 for “bbb.co.jp”, and an electronic device having “aaa.com” as a domain. For mail, storage processing and transmission processing are performed using the storage area 60-1, and for e-mail having “bbb.co.jp” as a domain, storage processing and transmission processing are performed using the storage area 60-2. Do.

  Note that the server 10 may perform storage processing of e-mail by sharing a storage area among a plurality of domains. For example, if the specific data of the received email is the same as the specific data of the email of another domain already stored in the storage area, the server 10 uses the received specific data of the email as the specific data reference information. It may be rewritten and stored. Then, when transmitting the e-mail, the specific data reference information may be written back into the specific data and transmitted.

  More specifically, the server 10 has the destination of the received electronic mail M8 as “userA@bbb.co.jp”, and the attached file data F1 (an example of specific data) of the electronic mail M8 is stored in a specific area. If it is the same as the attached file data F1 included in the e-mail M2 whose destination is “userA@aaa.com” already stored in 80 (storage area 60 in a broad sense), the attached file data F1 of the e-mail M8 is Then, the specific data reference information “002-1” is rewritten, and the rewritten electronic mail M8 is stored in the specific area 80. For example, when the server 10 receives an email reception request for the user A of the domain “bbb.co.jp” from the terminal 20, the specific data reference information “002” of the email M8 read from the specific area 80 is received. The attached file data F1 corresponding to “1” is written back, and the written email M8 is transmitted to the terminal.

  Further, when the server 10 receives an e-mail in which a plurality of destinations having different domains are designated, the server 10 stores the e-mail reference information in each mailbox of each destination, and the received e-mail in the storage area. You may make it store.

  For example, when the server 10 receives the e-mail M9 in which “userA@aaa.com” and “userA@bbb.co.jp” are specified, the server 10 receives the e-mail M9 in each user's mailbox corresponding to each destination. The electronic mail reference information (for example, “009”) corresponding to the electronic mail M9 is stored, and one electronic mail M9 is stored in the specific area 80 (storage area 60 in a broad sense). For example, when the server 10 receives an e-mail reception request for the user A of the domain “bbb.co.jp” from the terminal 20, the server 10 stores the electronic mail stored in the mailbox of the user A of “bbb.co.jp”. Based on the mail reference information “009”, the electronic mail M9 is read from the specific area 80, and the read electronic mail M9 is transmitted to the terminal 20.

  As described above, in this embodiment, when the server 10 manages a plurality of domains, the storage area can be further saved.

7). Description of Decoding Process Attached file data (for example, image data) whose original data is binary data is encoded by various encoding methods such as “base64” and “quoted-printable” in e-mail ( Encoded). Therefore, although the encoding method is different, data having the same contents may be duplicated and stored in the storage area.

  Therefore, the server 10 according to the present embodiment may decode (decode) the encoded specific data of the received electronic mail and perform processing based on the decoded specific data. That is, a process for determining whether or not the decrypted specific data is already stored in the storage area 60 (for example, the specific area 80) may be performed.

  For example, when the decrypted specific data of the received electronic mail is not included in another electronic mail already stored in the storage area 60, that is, the server 10 hashes the hash value of the decrypted specific data. If the hash value is not registered in the table TB, the hash value is registered in association with the specific data reference information of the decrypted specific data, and the e-mail is stored in the storage area 60. The specific data of the e-mail is stored in a decrypted state.

  On the other hand, when the decrypted specific data of the received email is included in another email already stored in the storage area 60, the server 10 has the hash value of the decrypted specific data hashed. If registered in the table TB, the specific data is rewritten to specific data reference information corresponding to the hash value, and the rewritten electronic mail is stored in the storage area 60.

  The server 10 stores the encoding method of the specific data at the time of receiving the mail when decoding the specific data, and refers to the encoding method of the specific data when sending the e-mail to the terminal 20. Then, the specific data is encoded and transmitted.

  The server 10 performs the following process when performing the decryption process. First, when the e-mail is in a single part format, the encoding method is detected with reference to “Content-Transfer-Encoding” in the header, and the body is decoded according to the encoding method. For example, if the encoding method is “base64”, a decoding process based on “base64” is performed, and if the encoding method is “quoted-printable”, a decoding process based on “quoted-printable” is performed. When the electronic mail is in a multi-part format, the encoding method is detected by referring to “Content-Transfer-Encoding” in the part header, and the part data is decoded according to the encoding method.

  In this way, although only the encoding method is different, it is not necessary to store the original data in duplicate for the same specific data, so that the storage area can be saved.

10 server, 100 processing unit, 110 delivery support unit (SMTP), 111 receiving unit,
112 storage processing unit, 113 delivery unit, reception correspondence unit (POP / IMAP),
121 reception unit, 122 transmission unit, 123 reference determination unit, 124 deletion unit,
50 storage units, 60 storage areas, 70 mailboxes, 80 specific areas,
180 information storage media, 20 terminals, 21 MUA

Claims (2)

A program for a server that performs processing for storing received email in a storage area and transmitting the stored email,
A receiving unit that performs processing to receive an email;
A storage processing unit for storing the e-mail in the storage area when an e-mail addressed to a user under the server management is received;
A transmission unit that performs a process of reading an e-mail from the storage area and transmitting the read e-mail to the terminal when an e-mail reception request is received from the terminal;
For each email stored in the storage area, a reference determination unit that sets a reference value for the email and determines whether the email is referenced based on the reference value;
The computer is caused to function as a deletion unit that performs processing for deleting an e-mail that is determined not to be referenced from the storage area,
The storage processing unit
When the attached file data included in the received e-mail is included in another e-mail already stored in the storage area, the attached file data is rewritten with the specific data reference information, and the rewritten e-mail is Perform processing to store in the storage area,
The transmitter is
When the specific data reference information is included in the email read from the storage area, the specific data reference information is written back to the attached file data, and the written email is transmitted to the terminal. ,
The reference determination unit
The process of adding the number of addresses of the e-mail to the e-mail reference value in which a predetermined value is set in advance, and the number of times the e-mail is rewritten to specific data reference information based on the attached file data of the e-mail And adding to
A process of subtracting the number of destinations to which the e-mail has been transmitted from the reference value of the e-mail, and a process of subtracting the number of times written back to the attached file data from the specific data reference information from the reference value of the e-mail Done
A program for determining that an e-mail is not referred to when the reference value of the e-mail is a predetermined value. A server that stores received emails in a storage area and performs processing for transmitting the stored emails,
A receiving unit that performs processing to receive an email;
A storage processing unit for storing the e-mail in the storage area when an e-mail addressed to a user under the server management is received;
A transmission unit that performs a process of reading an e-mail from the storage area and transmitting the read e-mail to the terminal when an e-mail reception request is received from the terminal;
For each email stored in the storage area, a reference determination unit that sets a reference value for the email and determines whether the email is referenced based on the reference value;
A deletion unit that performs a process of deleting an e-mail that is determined not to be referenced from the storage area, and the storage processing unit includes:
When the attached file data included in the received e-mail is included in another e-mail already stored in the storage area, the attached file data is rewritten with the specific data reference information, and the rewritten e-mail is Perform processing to store in the storage area,
The transmitter is
When the specific data reference information is included in the email read from the storage area, the specific data reference information is written back to the attached file data, and the written email is transmitted to the terminal. ,
The reference determination unit
The process of adding the number of addresses of the e-mail to the e-mail reference value in which a predetermined value is set in advance, and the number of times the e-mail is rewritten to specific data reference information based on the attached file data of the e-mail And adding to
A process of subtracting the number of destinations to which the e-mail has been transmitted from the reference value of the e-mail, and a process of subtracting the number of times written back to the attached file data from the specific data reference information from the reference value of the e-mail Done
A server that determines that the e-mail is not referred to when the reference value of the e-mail is a predetermined value.

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