JP5150402B2 - Communication control device and communication control program - Google Patents

Description

  The present invention relates to a communication control device and a communication control program, and relates to a technique for sending an e-mail to a destination by adding a mail address indicating a transmission source.

Conventionally, an e-mail is transmitted to a destination with a sender e-mail address indicating a sender of the e-mail (hereinafter, the e-mail address is simply referred to as an address). However, when the transmission source address added to the electronic mail is registered as a transmission destination address such as spam by a third party, a so-called junk mail may be transmitted to the transmission source address. In this case, even if the user wants to invalidate the source address, it is not a good idea to invalidate the address when the address is known to the parties concerned. As a technique for solving this problem, for example, a communication system shown in Patent Document 1 below has been proposed. This communication system uses the "real address" that is the original address, the "intermediate address" that is used only when delivering mail within the company, and the "external address" that is used when sending e-mail to the outside. In doing so, by converting addresses between these "real addresses", "intermediate addresses" and "external addresses", the "real addresses" are not exposed to the outside or mail transfer service providers. .
JP 2006-309604 A

  However, since the communication system disclosed in Patent Document 1 can transmit an e-mail after being converted to an “external address” through a conversion from “real address” to “intermediate address”, Unless the “intermediate address” is used, the leakage of the “real address” cannot be prevented. In addition, there is a one-to-one correspondence between “real address”, “intermediate address”, and “external address”, and it is easy to find “real address” from “external address”. It is not possible to increase sex.

  The present invention has been made to solve the above-described problem, and can convert an original source address directly into a plurality of pseudo external source addresses, and leakage of the original source address. The purpose is to increase the certainty of prevention.

The invention according to claim 1 of the present invention is a transmission destination address analysis unit for analyzing a transmission destination address of an e-mail designated by a user;
A source address analyzing unit for analyzing a source address indicating a source of the email;
An external sender address that is different from the source address by adding an identifier that is sequentially generated according to a predetermined rule to the source address analyzed by the source address analyzing unit. An address conversion unit for converting to
Instead of the source address, a mail transmitting unit that transmits the electronic mail to the destination address using the external sender address ;
A mail receiver for receiving e-mails from a networked computer;
In the e-mail received by the mail receiving unit, the destination address used as the address indicating the destination of the e-mail matches the external sender address generated in the past by the conversion by the address converting unit. A determination unit for determining whether or not
If the determination unit determines that the received e-mail destination address matches the externally generated sender address, the received e-mail destination address is set in advance. Based on the stored restoration information, perform a first restoration process to restore the source address before being converted to the external sender address determined to match,
If the determination unit determines that a destination address of the received e-mail does not match the externally generated sender address, the reception is performed based on the predetermined rule. An address restoration unit for performing a second restoration process for restoring the transmission destination address of the received e-mail to the source address before conversion;
The received e-mail is delivered to the source address restored by the first restoration process, while the received address is delivered to the source address restored by the second restoration process. An electronic mail distribution unit that distributes address invalid information indicating that the destination address of the electronic mail is invalid without delivering the electronic mail .

The invention according to claim 4 is a transmission destination address analysis unit for analyzing a transmission destination address of an e-mail designated by a user;
A source address analyzing unit for analyzing a source address indicating a source of the email;
An external sender address that is different from the source address by adding an identifier that is sequentially generated according to a predetermined rule to the source address analyzed by the source address analyzing unit. An address conversion unit for converting to
Instead of the source address, a mail transmitting unit that transmits the electronic mail to the destination address using the external sender address ;
A mail receiver for receiving e-mails from a networked computer;
In the e-mail received by the mail receiving unit, the destination address used as the address indicating the destination of the e-mail matches the external sender address generated in the past by the conversion by the address converting unit. A determination unit for determining whether or not
If the determination unit determines that the received e-mail destination address matches the externally generated sender address, the received e-mail destination address is set in advance. Based on the stored restoration information, perform a first restoration process to restore the source address before being converted to the external sender address determined to match,
If the determination unit determines that a destination address of the received e-mail does not match the externally generated sender address, the reception is performed based on the predetermined rule. An address restoration unit for performing a second restoration process for restoring the transmission destination address of the received e-mail to the source address before conversion;
The received e-mail is delivered to the source address restored by the first restoration process, while the received address is delivered to the source address restored by the second restoration process. A communication control program for causing a computer to function so as to include an e-mail delivery unit that delivers address invalid information indicating that the destination address of the e-mail is invalid without delivering the e-mail It is.

  In these inventions, the address conversion unit adds a source address that is analyzed by the source address analysis unit and used when sending an e-mail, and an identifier that is sequentially generated according to a predetermined rule, to the source address. Thus, the mail address is converted into an external sender address that is different from the sender address, and the mail transmitting unit transmits an email using the converted sender address instead of the original sender address. Therefore, when sending an e-mail, the original sender address can be prevented from leaking by adding the above identifier, and the sender address can be directly converted into a pseudo external sender address for the outside. Yes. In the present invention, since the address conversion unit adds identifiers sequentially generated according to a predetermined rule to the source address, a plurality of pseudo external sender addresses can be obtained from one source address. Since it can be generated and converted, it becomes difficult for a third party to find the original source address from the sender address for the outside, and the certainty of preventing the leakage of the original source address can be improved. . The “address” in the claims, the means for solving the problems, and the effect of the invention means “mail address”.

  According to this invention, when the determination unit determines that the transmission destination address of the received e-mail matches the externally generated sender address, the address restoration unit sets the transmission destination address. Based on the restoration information held in advance, the sender address is restored to the source address before the externally determined sender address determined to match, and the e-mail delivery unit restores the restored sender address Even if the recipient who received the e-mail with the external sender address added returns the e-mail based on the external sender address, The e-mail is surely returned to the sender of the e-mail by the e-mail delivery unit.

  According to the present invention, the address restoration unit is configured so that even if the determination unit determines that the destination address of the received e-mail does not match the externally generated sender address, Based on the established rules, the sender address of the received e-mail is restored to the sender address before conversion, and the e-mail delivery unit sends the sender address to the sender address by the address restorer If the restoration process is established, address invalid information indicating that the destination address of the e-mail is invalid is delivered to the restored source address without delivering the received e-mail. So, for example, a spammer falsifies an address that it owns to generate a new address, and the new address that has been falsified happens to be E-mail sent back by sending the above address invalid information to the sender of the sender address (sender who sent an e-mail using the sender address) when it approximated the original sender address Can be notified that the source address may have been altered.

The invention according to claim 2 is the communication control device according to claim 1 , wherein the address conversion unit is predetermined when converting the source address to the external sender address. Display name information is further added.

  According to this invention, since the address conversion unit further adds predetermined display name information at the time of conversion to the external sender address, even if the source address is changed to the external sender address, A recipient who receives an e-mail to which the converted external sender address is added can easily recognize the source of the external sender address based on the added display name information.

The invention according to claim 3 is the communication control device according to claim 1 or 2 , wherein the address conversion unit converts the address at the time of conversion from the source address to the external sender address. This stores mail transmission time information including time, transmission source address, and transmission destination address.

  According to the present invention, the address conversion unit stores the mail transmission time information including the address conversion time, the transmission source address, and the transmission destination address during the conversion process from the transmission source address to the external sender address. Based on the above-mentioned information at the time of mail transmission, it is possible to trace the route of how the other party who has replied using the external sender address has acquired and sent back the external sender address. It becomes possible. For example, when a spammer returns or transmits a spam mail using the external sender address, it is possible to track who the email sent to the past was used by the spammer.

  According to the present invention, the original transmission source address can be directly converted into a plurality of pseudo external transmission source addresses, and the certainty of preventing leakage of the original transmission source address can be improved.

  Hereinafter, a communication control device and a communication control program according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a communication system including a communication control apparatus according to an embodiment of the present invention.

  The communication system 1 includes an SMTP server 10 as a communication control apparatus according to an embodiment of the present invention, one or more personal computers (hereinafter referred to as PCs) 14a and 14b, and a multifunction machine 15. The communication system 1 is configured such that the SMTP server 10, the PCs 14a and 14b, and the multifunction device 15 are connected to each other via a LAN (Local Area Network) 4 or the like so that various data can be transmitted and received.

  The communication system 1 is used, for example, in a company or the like, and the network in the company is configured by the LAN 4, and the devices used by users such as employees in the company are the multifunction machine 15 and the PCs 14a and 14b. It becomes.

  The multifunction machine 15 is a digital copying machine having complex functions such as a scanner function, a facsimile function, a printer function, and a copy function. In the multi-function device 15, various functions are realized by combining the above-described functions. For example, a scanner function, a PC transmission function, an E-mail transmission function, a FAX transmission function, and the like are realized.

  Here, the PC transmission function is a function for directly transmitting image data read from a document from the multifunction machine 15 to an arbitrary PC 14 or the like via the LAN 4. The E-mail transmission function transmits image data read from a document as an email attachment file from the multifunction machine 15 to the SMTP server 10 via the LAN 4, and the SMTP server 10 transmits other PCs 14a, 14b, This is a function of transmitting image data read from a document as an attached file of an e-mail by transmitting an e-mail to an external PC 24, 25, etc. via the Internet 6. The FAX transmission function is a function for directly transmitting image data read from a document from an MFP 15 to an arbitrary facsimile machine or the like via a telephone line.

  The SMTP server 10 is communicably connected to the destination PCs 24 and 25 via the Internet 6 or the like, and transmits and receives e-mails between the PCs 14a and 14b and the multi-function device 15 and the destination PCs 24 and 25. It is possible.

  The SMTP server 10 includes a CPU 100 and a storage device 108. The CPU 100 executes a communication control program, which will be described later, under the control of the operating system, whereby a transmission destination address analysis unit 101, a transmission source address analysis unit 102, an address conversion unit 103, a mail transmission / reception unit 104, It functions as a determination unit 105, an address restoration unit 106, and a mail delivery unit 107.

  When the user sends an email transmission instruction to the SMTP server 10, the transmission destination address analysis unit 101 simply sends a transmission destination email address (hereinafter, a mail address) as transmission destination information of the email. Address). The transmission destination address analyzed by the transmission destination address analysis unit 101 is used for mail transmission to the external PCs 24 and 25 by the mail transmission / reception unit 104.

  The transmission source address analysis unit 102 analyzes a transmission source address, which is transmission source information indicating a sender (transmission source) of the e-mail when the user instructs the SMTP server 10 to transmit the e-mail. . The sender address analyzed by the sender address analyzing unit 102 is information indicating the sender of the email in the email to be sent when the email sending / receiving unit 104 sends the email to the external PC 24, 25, etc. Add as

  The address conversion unit 103 is different from the transmission source address by adding the transmission source address analyzed by the transmission source address analysis unit 102 to the transmission source address with an identifier sequentially generated according to a predetermined rule. Performs processing to convert to an external sender address.

  The mail transmission / reception unit (mail transmission unit, mail reception unit) 104 is based on an email transmission instruction from the user using the PCs 14a, 14b or the multifunction machine 15 (hereinafter, an output process of an email transmission instruction, In the case of explaining e-mail transmission / reception processing, the notation of the MFP 15 is omitted), and the e-mail is transmitted to the external PCs 24, 25, etc., with respect to the transmission destination address analyzed by the transmission destination address analysis unit 101 To do. Further, the mail transmitting / receiving unit 104 receives an electronic mail from the external PCs 24, 25, etc. via the Internet 6. The mail transmission / reception unit 104 is analyzed by the transmission destination address analysis unit 101 using the external sender address converted by the address conversion unit 103 instead of the transmission source address analyzed by the transmission source address analysis unit 102. Send an e-mail to the destination address.

  In the e-mail received by the e-mail transmission / reception unit 104, the determination unit 105 uses an external address generated in the past by the conversion by the address conversion unit 103 as the transmission destination address used as the address indicating the transmission destination of the e-mail. It is determined whether or not it matches the destination sender address.

  The address restoration unit 106 is determined by the determination unit 105 that the transmission destination address of the email received by the mail transmission / reception unit 104 matches the external sender address generated in the past by the conversion by the address conversion unit 103. In this case, on the basis of the predetermined rule used by the address conversion unit 103 for conversion from the source address to the address with destination, an external sender address determined to match the destination address is generated. Is restored to the source address before being sent.

  The mail distribution unit 107 distributes the e-mail received by the mail transmitting / receiving unit 104 to the transmission source address of the e-mail restored by the address restoration unit 106.

  The storage device 108 is composed of, for example, a magnetic disk such as an HDD, and stores an operating system that is a basic program for overall control of the SMTP server 10, a communication control program according to an embodiment of the present invention, and the like. When the communication control program is recorded on a recording medium such as a CD-ROM or a flexible disk, the communication control program is stored in the storage device 108 by installing the recording medium in a recording medium driving device (not shown). . If the program is stored in a WEB server on the Internet, the program may be stored in the storage device 108 by downloading the communication program from the WEB server. The CPU 100 operates in accordance with the communication control program stored in the storage device 108, so that the transmission destination address analysis unit 101, the transmission source address analysis unit 102, the address conversion unit 103, and the mail transmission / reception unit 104 described above. And the determination unit 105, the address restoration unit 106, and the mail delivery unit 107.

  The configuration of the communication system 1 described above can be variously changed. The number of the MFPs 15 and PCs 14a and 14b connected via the LAN 4 or the like can be changed, or the LAN 4 and the Internet 6 can be connected. In addition to the SMTP server 10, a gateway, a router, and the like may be provided as appropriate.

Next, a first embodiment of the e-mail transmission process by the SMTP server 10 and the communication system 1 will be described. FIG. 2 is a diagram showing an outline of communication between the PC, the SMTP server, and the external PC during the e-mail transmission process. FIG. 3 is a flowchart showing the flow of processing among the PC, SMTP server and external PC during the e-mail transmission process. FIG. 4 is a block diagram showing various types of information and processing handled by the PC, SMTP server, and external PC. FIG. 5 is a diagram illustrating an example of a source address, an identifier, and an external sender address.
The numbers in parentheses (1) to (7) below correspond to the numbers in parentheses shown in FIG. 2 (S1 to S21 correspond to FIG. 3).

  (1) First, from the PC 14a or 14b in the communication system 1, to the SMTP server 10 by the operation of the user, e-mail data to be transmitted, the transmission destination address indicating the transmission destination, and transmission A transmission instruction for the e-mail is transmitted together with a formal sender address unique to the user indicating the user who is a person (S1). At the time of sending the e-mail, a user-specific user ID (user identification code) may be sent from the PC 14a or 14b to the SMTP server 10 according to the user's instruction instead of the transmission source address. That is, as information indicating the transmission source of the e-mail, other information such as a user ID may be used without using an address.

  (2) When the SMTP server 10 receives from the PC 14a or 14b the various types of data and transmission instructions for transmitting the email, the transmission destination address analyzing unit 101 of the SMTP server 10 receives the received various types of data for transmitting the email. Then, the transmission destination address added to the electronic mail is analyzed and acquired (S11). Further, the transmission source address analyzing unit 102 analyzes and acquires the transmission source address added to the electronic mail from the received various data for electronic mail transmission (S12).

  Then, the address conversion unit 103 adds an identifier that is sequentially generated according to a predetermined rule to the analyzed source address, so that the source address is transmitted to the outside different from the source address. Is converted into a user address (S13). For example, as shown in FIG. 5, if the source address is “osaka@kyoceramita.co.jp”, the address conversion unit 103 adds “ An identifier such as “_7t12fx” is added, and the original source address is converted into a different external sender address “osaka_7t12fx@kyoceramita.co.jp”. That is, the address conversion unit 103 stores, for example, (a) a plurality of character strings made up of combinations of alphanumeric symbols as identifiers (identifiers sequentially generated according to a predetermined rule) to be added to the source address. Select one character string at random from the identifier storage table and use the selected character string, or (b) generate and use a combination of a plurality of alphanumeric symbols using a random number for each address conversion process. And so on. However, the identifier used for the address conversion by the address conversion unit 103 is preferably different every time regardless of the external sender address.

  In addition, when a user-specific user ID or the like is used instead of the transmission source address when the electronic mail is instructed to be transmitted, “@” and a domain name (for example, “kyoceramita.co.jp” or the like after the identifier) ) To create a new external sender address, for example, “7t12fx@kyoceramita.co.jp” from the user ID, and convert the user ID into an external sender address.

  By performing the address conversion processing as described above, the address conversion unit 103 can directly convert the original source address into a plurality of pseudo external sender addresses.

  Further, the address conversion unit 103 stores the transmission time information (transmission time, serial number, transmission source address, transmission destination address, identifier used for the address conversion, etc.) of the electronic mail (S14).

  (3) The mail transmitting / receiving unit 104 of the SMTP server 10 adds the converted external sender address to the electronic mail as transmission source information indicating the transmission source, and the electronic mail is transmitted to the transmission destination address analyzing unit 101. Is transmitted via the Internet 6 to the external PC 24 or 25 indicated by the transmission destination address analyzed by (S15).

  Thereafter, the external PC 24 or 25 indicated by the transmission destination address receives the electronic mail transmitted from the mail transmitting / receiving unit 104 of the SMTP server 10 via the Internet 6 (S21).

  Next, e-mail reception processing by the SMTP server 10 and the communication system 1 will be described. Description will be made with reference to FIGS. 6 to 9 in addition to FIGS. FIG. 6 is a flowchart showing the flow of processing among the PC, SMTP server and external PC at the time of e-mail reception processing. FIG. 7 is a diagram illustrating an example of a transmission destination address, an external sender address generated in the past, an identifier, and a restored transmission source address. 8 and 9 are diagrams showing examples of transmission destination addresses, identifiers, and restored transmission source addresses. Similarly to the above, the numbers in parentheses below correspond to the numbers in parentheses shown in FIG.

  (4) When the external PC 24 or 25 transmits an e-mail addressed to an address having a domain managed by the SMTP server 10 of the communication system 1 via the Internet 6 (S101), the SMTP of the communication system 1 The mail transmitting / receiving unit 104 of the server 10 receives the electronic mail (S111). At this time, the external PC 24 or 25 transmits the mail in a format for replying to the e-mail with the external sender address converted by the SMTP server 10 or the external PC converted by the SMTP server 10. It is assumed that the outgoing sender address is obtained from another person and the external sender address is used as a mail transmission destination.

  (5) When the mail transmission / reception unit 104 of the SMTP server 10 receives the e-mail (S111), the determination unit 105 determines the transmission destination address indicating the transmission destination of the e-mail from various data accompanying the e-mail. And the sender address indicating the sender (source) of the e-mail is obtained by analysis (S112, S113).

  Then, the determination unit 105 determines whether or not the analyzed destination address matches any one of the external sender addresses generated in the past by the conversion by the address conversion unit 103 (S13 in FIG. 3). (S114). At this time, the determination unit 105 performs the determination based on the transmission time information of the email stored in the address conversion unit 103 at the time of each external sender address conversion.

If the determination unit 105 determines that the transmission destination address matches one of the external sender addresses generated in the past by the address conversion unit 103 (YES in S114), the address restoration unit 106 Using the restoration information held in advance, a restoration process (in which the destination address analyzed in S112 is restored to the source address before the external sender address determined to match in S114 is generated) Reverse address conversion processing) is performed (S119). The address restoration unit 106 stores the predetermined rule used for the address conversion (S13) stored in the address conversion unit 103 or the transmission of the e-mail as the restoration information held in advance. Use time information.

  Here, for example, when the address restoration unit 106 uses the predetermined rule as restoration information, as shown in FIG. 7, the analyzed destination address is “osaka_7t12fx@kyoceramita.co.jp”. , If it matches with “osaka_7t12fx@kyoceramita.co.jp” generated in the past, the identifier “_7t12fx used in the past address conversion based on the predetermined rule stored in the address conversion unit 103” ”Is searched for and the identifier“ _7t12fx ”is removed from the local part“ osaka_7t12fx ”at the address, and the original source address“ osaka@kyoceramita.co.jp ”is restored.

  Note that, when the electronic mail is instructed to be transmitted (S1 in FIG. 3), the user ID unique to the user is used instead of the source address, and for example, as shown in FIG. When the address is “7t12fx@kyoceramita.co.jp”, the address restoration unit 106 uses the identifier used in the past address translation based on the predetermined rule stored in the address translation unit 103. Search for “7t12fx” to find the source address stored in the address translation unit 103 in association with the source address before conversion of the identifier “7t12fx”, for example, “osaka@kyoceramita.co.jp” As a result, the analyzed transmission destination address “7t12fx@kyoceramita.co.jp” is restored to “osaka@kyoceramita.co.jp” which is the original transmission source address.

  (6) The mail delivery unit 107 delivers the electronic mail received by the mail transmission / reception unit 104 to the restored original transmission source address (S120). Thereafter, the user's PC 14a or 14b indicated by the transmission source address receives the electronic mail (S131).

  On the other hand, even if the determination unit 105 determines in S114 that the transmission destination address does not match any of the external sender addresses generated in the past by the address conversion unit 103 (S114). NO), the address restoring unit 106 stores the destination address analyzed in S112 using the predetermined rule stored in the address converting unit 103 and used for the address conversion (S13 in FIG. 3). Is restored to the source address before the external sender address determined to match in S114 (reverse address conversion process) is tried (S115).

  Here, for example, as illustrated in FIG. 9, the address restoration unit 106 has the analyzed destination address “osaka_7t13fx@kyoceramita.co.jp”, and any external sender address generated in the past. If there is no match, the plurality of identifiers “_7t12fx” and the like used in the past address conversion are searched and found based on the predetermined rule stored in the address conversion unit 103. In the local part “osaka — 7t13fx”, the part occupied by the identifier and the essential part indicating the local part in the original source address are analyzed. Based on the analysis, the address restoration unit 106 discriminates, for example, a procedure for adding seven alphanumeric symbols as an identifier as an identifier from the predetermined rule, and the essential in the local part of the original source address. If the part “osaka” can be extracted, the address restoration unit 106 uses the analyzed destination address “osaka_7t13fx@kyoceramita.co.jp” as the original source address “osaka@kyoceramita.co.jp”. To "".

  (7) If the address restoration by the address restoration unit 106 is successful (YES in S116), the mail delivery unit 107 does not deliver the received e-mail to the restored source address. Then, address invalid information indicating that the transmission destination address of the electronic mail is invalid is distributed (S117).

  If the address restoration by the address restoration unit 106 is not successful (NO in S116), the mail transmission / reception unit 104 receives log information such as the reception time of the received electronic mail, the sender address indicating the sender, and the like. Is stored (S118). In addition, in the case where the address restoration by the address restoration unit 106 is successful (YES in S116), the mail transmitting / receiving unit 104 performs log information such as the reception time of the received electronic mail, the sender address indicating the sender, and the like. May be stored.

  Next, a second embodiment of the e-mail transmission process by the SMTP server 10 and the communication system 1 will be described. FIG. 10 is a flowchart showing the flow of processing among the PC, SMTP server and external PC during the e-mail transmission process. FIG. 11 is a diagram illustrating an example of an external sender address to which display name information is added. The description of the same processing as that of the first embodiment shown in FIG. 4 is omitted.

  An e-mail transmission instruction is transmitted from the PC 14a or 14b in the communication system 1 to the SMTP server 10 by a user operation (S201), and the address conversion unit 103 of the SMTP server 10 sets the transmission source address to the transmission source address. When converting to an external sender address different from (S213), predetermined display name information (such as display name defined in RFC2200) is further added (S214). For example, when the transmission instruction of the e-mail is used, a user-specific user ID or the like is used instead of the transmission source address, and the address conversion unit 103 adds “@” and a domain name (for example, after the identifier described above) When adding a new external sender address from the user ID by adding “kyoceramita.co.jp” or the like), the address conversion unit 103 sets the source address to “osaka @ When it is “kyoceramita.co.jp”, the address conversion unit 103 adds display name information and generates an external sender address consisting of “Osaka <7t12fx@kyoceramita.co.jp>”.

  Then, the mail transmitting / receiving unit 104 transmits the e-mail to the external PC 24 or 25 indicated by the destination address using the external sender address to which the display name information is added (S216).

  By adding the display name information to the external sender address in this way, the external PC 24 or 25 that has received the e-mail can display the above-described information indicating the source of the received e-mail when the mailer displays the display. Since the sender address “Osaka <7t12fx@kyoceramita.co.jp>” to which the display information is added is displayed, the user of the external PC 24 or 25 can easily recognize the sender of the received e-mail. be able to.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above embodiment, the SMTP server 10 holds the restoration information, and performs the conversion process from the source address to the external sender address and the reverse conversion process from the external sender address to the source address. However, the present invention is not limited to this configuration. For example, the SMTP server 10 does not hold the restoration information, and does not perform the conversion process from the transmission source address to the external sender address and the reverse conversion process from the external sender address to the transmission source address. The other computer that is connected to the communication system 1 and forms part of the communication system 1 is responsible for the restoration process, the address conversion process, and the address reverse conversion process. (1) The PC 14a or 14b first sends an e-mail And the computer performs an address conversion process, and the SMTP server 10 receives an e-mail to be transmitted and an external sender address from the computer and transmits them to the external PC 24 or 25, and (2) an SMTP server. 10. When an e-mail is received from the external PC 24 or 25, the e-mail After sending to the computer in charge of the restoration process and performing the restoration process (address reverse conversion process) in the computer, the SMTP server 10 delivers the email or address invalid information received from the computer to the PC 14a or 14b. Alternatively, the electronic mail may not be distributed.

  In the above embodiment, in the SMTP server 10, a communication control program is stored in the storage device 108, and the CPU 100 operates based on the communication control program, so that the CPU 100 performs the transmission destination address analysis unit 101. And the source address analysis unit 102, the address conversion unit 103, the mail transmission / reception unit 104, the determination unit 105, the address restoration unit 106, and the mail distribution unit 107. These parts may be provided in the SMTP server 10 as a separate circuit from the CPU 100 regardless of the operation of the CPU 100 based on the operation.

It is a figure which shows the communication system provided with the communication control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the communication outline between PC, an SMTP server, and external PC at the time of an electronic mail transmission process. It is a flowchart which shows the flow of a process between PC, an SMTP server, and an external PC at the time of an electronic mail transmission process. It is a block diagram which shows the various information and processes handled by PC, SMTP server, and external PC. It is a figure which shows the example of a transmission source address, an identifier, and the sender address for the outside. It is a flowchart which shows the flow of a process between PC, an SMTP server, and an external PC at the time of an e-mail reception process. It is a figure which shows the example of a transmission destination address, the sender address for the outside produced | generated in the past, an identifier, and the restored transmission source address. It is a figure which shows the example of a transmission destination address, an identifier, and the restored transmission source address. It is a figure which shows the example of a transmission destination address, an identifier, and the restored transmission source address. It is a flowchart which shows the flow of a process between PC, an SMTP server, and an external PC at the time of an electronic mail transmission process. It is a figure which shows the example of the sender address for the outside to which display name information was added.

Explanation of symbols

1 Communication System 6 Internet 10 SMTP Server 100 CPU
101 transmission destination address analysis unit 102 transmission source address analysis unit 103 address conversion unit 104 mail transmission / reception unit 105 determination unit 106 address restoration unit 107 mail distribution unit 108 storage device 15 multifunction device

Claims (4)

A destination address analysis unit for analyzing the destination address of the email specified by the user;
A source address analyzing unit for analyzing a source address indicating a source of the email;
An external sender address that is different from the source address by adding an identifier that is sequentially generated according to a predetermined rule to the source address analyzed by the source address analyzing unit. An address conversion unit for converting to
Instead of the source address, a mail transmitting unit that transmits the electronic mail to the destination address using the external sender address ;
A mail receiver for receiving e-mails from a networked computer;
In the e-mail received by the mail receiving unit, the destination address used as the address indicating the destination of the e-mail matches the external sender address generated in the past by the conversion by the address converting unit. A determination unit for determining whether or not
If the determination unit determines that the received e-mail destination address matches the externally generated sender address, the received e-mail destination address is set in advance. Based on the stored restoration information, perform a first restoration process to restore the source address before being converted to the external sender address determined to match,
If the determination unit determines that a destination address of the received e-mail does not match the externally generated sender address, the reception is performed based on the predetermined rule. An address restoration unit for performing a second restoration process for restoring the transmission destination address of the received e-mail to the source address before conversion;
The received e-mail is delivered to the source address restored by the first restoration process, while the received address is delivered to the source address restored by the second restoration process. An electronic mail distribution unit that distributes address invalid information indicating that the destination address of the electronic mail is invalid without delivering the electronic mail . The communication control device according to claim 1, wherein the address conversion unit further adds predetermined display name information when converting the source address to the external sender address. Said address translation unit, when converting from the source address to the external facing sender address, the address translation time, source address, claim stores the mail transmission time information including a transmission destination address 1 or 2 The communication control device according to 1. A destination address analysis unit for analyzing the destination address of the email specified by the user;
A source address analyzing unit for analyzing a source address indicating a source of the email;
An external sender address that is different from the source address by adding an identifier that is sequentially generated according to a predetermined rule to the source address analyzed by the source address analyzing unit. An address conversion unit for converting to
Instead of the source address, a mail transmitting unit that transmits the electronic mail to the destination address using the external sender address ;
A mail receiver for receiving e-mails from a networked computer;
In the e-mail received by the mail receiving unit, the destination address used as the address indicating the destination of the e-mail matches the external sender address generated in the past by the conversion by the address converting unit. A determination unit for determining whether or not
If the determination unit determines that the received e-mail destination address matches the externally generated sender address, the received e-mail destination address is set in advance. Based on the stored restoration information, perform a first restoration process to restore the source address before being converted to the external sender address determined to match,
If the determination unit determines that a destination address of the received e-mail does not match the externally generated sender address, the reception is performed based on the predetermined rule. An address restoration unit for performing a second restoration process for restoring the transmission destination address of the received e-mail to the source address before conversion;
The received e-mail is delivered to the source address restored by the first restoration process, while the received address is delivered to the source address restored by the second restoration process. A communication control program for causing a computer to function so as to include an e-mail delivery unit that delivers address invalid information indicating that the destination address of the e-mail is invalid without delivering the e-mail .

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