JP2005208745A - Email terminal, email system and email terminal control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an email terminal, an email system and an email terminal control program that can prevent leakage of secrets even when an email sender specifies a wrong destination. <P>SOLUTION: The email terminal creates an email (S100), receives destination addresses (S101) and receives an attribute of the email from a user (S102). If a sending command is received (S103: YES), a sending condition database 106 is referred to (S104), and if sending conditions reject any sending (S105: NO), the corresponding email address is deleted from the email destinations (S108). If there is an unprocessed email address (S106: YES), the sending conditions are referred to about the next email address. If there is no unprocessed email address (S106: NO), the email is sent (S107). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to e-mail security protection, and more particularly, to a technique for preventing leakage of confidential information due to an e-mail destination error.

  In recent years, electronic mail services have become widespread, and electronic mail is used in various forms such as using a mobile phone in addition to so-called personal computer communication. Since such e-mails are usually transmitted and received via the Internet, there is a risk of information stealing and data tampering by a third party on the way. In particular, when the data is tampered with, the content of the e-mail becomes completely incomprehensible, or wrong content is received.

  A so-called digital signature technique has been developed for such a problem. For example, when a public key cryptosystem is used, the sender of the e-mail encrypts the e-mail with its own secret key and transmits it. The recipient of the email decrypts the email using the sender's public key. If the decryption is successful, the sender's validity is confirmed. This is because the secret key must be known in order to be correctly decrypted with the public key.

In addition, even when the electronic mail is falsified, it cannot be decrypted correctly, so that the recipient can detect the presence or absence of falsification by the digital signature. As described above, according to the digital signature technique, it is possible to detect tampering of an e-mail by a third party or to guarantee the validity of the sender (see, for example, Patent Document 1).
JP 2001-168902 A

  However, with digital signature technology, the e-mail is decrypted by specifying the required public key from the e-mail sender (FROM line), so even if the sender makes a mistake in the e-mail destination, There is a problem that the e-mail is decrypted. In particular, if the content of the e-mail is related to confidentiality, the result is that the confidentiality leaks to a third party.

  The present invention has been made in view of such a problem, and an electronic mail terminal and an electronic mail system capable of preventing leakage of confidential information even when an e-mail sender makes a wrong address And an electronic mail terminal control program.

  In order to achieve the above object, an electronic mail terminal according to the present invention is an electronic mail terminal that transmits an electronic mail, and includes attribute information acquisition means for acquiring attribute information related to the electronic mail, and destination information of the electronic mail. Destination information acquisition means for acquiring the transmission information, transmission permission determination means for determining whether the electronic mail can be transmitted to the destination indicated by the destination information from the attribute information and the destination information, and transmission permission determination means Transmission prohibiting means for prohibiting transmission of the electronic mail to a destination determined to be impossible to transmit.

In this way, when the sender of the e-mail makes a mistake in the destination, the e-mail is not transmitted to the destination, so that it is possible to prevent leakage of confidential information due to an e-mail destination error.
Further, in the electronic mail terminal according to the present invention, the transmission prohibition unit deletes the electronic mail from the electronic mail that is the destination address included in the electronic mail and is determined to be non-transmissible. It is characterized by. In this way, when an e-mail destination error is detected, transmission of the e-mail to the destination can be efficiently prohibited.

In addition, the electronic mail terminal according to the present invention includes a transmission availability storage unit that stores the availability of transmission of an email in association with the attribute information and the destination information, and the transmission availability determination unit includes the transmission availability storage unit. The e-mail can be transmitted or not by referring to the transmission / reception stored in the means.
In this way, fine transmission conditions can be set according to the attribute information and the destination information. Therefore, user convenience can be improved.

  Further, the electronic mail terminal according to the present invention includes electronic certificate-attached transmission means for attaching an electronic certificate to an electronic mail and transmitting the electronic certificate, and the transmission availability determination means is configured to transmit the attribute information and the attribute information in the transmission availability storage means. When the transmission permission / inhibition associated with the destination information is not stored, the electronic certificate-added transmission unit transmits the electronic mail to the destination according to the destination information.

In this way, it is possible to send an e-mail while protecting security even when no transmission condition is set in advance. Moreover, since this process can be performed without taking time and effort for the user, the convenience for the user can be improved.
The e-mail system according to the present invention is an e-mail system including an e-mail terminal that transmits an e-mail and an e-mail server that transfers the e-mail. Attribute information acquisition means for acquiring such attribute information, e-mail transmission means for transmitting the e-mail to the e-mail server, and attribute information transmission means for transmitting the attribute information to the e-mail server in association with the e-mail The e-mail server includes an e-mail receiving unit that receives an e-mail from the e-mail terminal, an attribute information receiving unit that receives attribute information associated with the e-mail, and destination information of the e-mail The destination information acquisition means for acquiring the destination information, the attribute information, and the destination information indicate the destination information. Transmission enable / disable determining means for determining whether or not the electronic mail can be transmitted to a destination; and transmission prohibiting means for prohibiting the transmission of the electronic mail to a destination determined to be impossible to transmit by the transmission enable / disable determining means. It is characterized by that.

In this way, when the sender of the e-mail makes a mistake in the destination, the e-mail is not transmitted to the destination, so that it is possible to prevent leakage of confidential information due to an e-mail destination error. Moreover, since the transmission condition is determined by the electronic mail server, the processing load on each electronic mail terminal can be reduced.
Further, in the electronic mail system according to the present invention, the transmission prohibition unit deletes the electronic mail from the electronic mail that is the destination address included in the electronic mail and that is determined to be impossible to transmit. It is characterized by.

In this way, when an e-mail destination error is detected, transmission of the e-mail to the destination can be efficiently prohibited.
In the electronic mail system according to the present invention, the electronic mail server includes transmission availability determination means for storing the availability of transmission of the email in association with the attribute information and the destination information, and the transmission availability determination means. Is characterized in that whether or not the electronic mail can be transmitted is determined by referring to whether or not transmission is possible, which is stored in the transmission availability storage means.

In this way, fine transmission conditions can be set according to the attribute information and the destination information. In addition, since transmission condition settings can be collectively maintained and managed by the e-mail server, the work cost for security protection can be reduced.
Also, in the electronic mail system according to the present invention, the electronic mail server includes an electronic certificate-attached transmission unit that transmits an electronic certificate with an electronic certificate attached thereto, and the transmission propriety determining unit is in the transmission propriety storing unit. When the transmission permission / inhibition associated with the attribute information and the destination information is not stored, the electronic certificate-added transmission unit causes the electronic mail to be transmitted to the destination according to the destination information. .

  In this way, it is possible to send an e-mail while protecting security even when no transmission condition is set in advance. Moreover, since this process can be performed without taking time and effort for the user, the convenience for the user can be improved. In addition, since maintenance and management of electronic certificates can be unified, work for security protection can be simplified.

  An electronic mail terminal control program according to the present invention is an electronic mail terminal control program executed by an electronic mail terminal that transmits an electronic mail, wherein the attribute information acquisition step of acquiring attribute information related to the electronic mail, A destination information acquisition step of acquiring destination information of the email, a transmission permission determination step of determining whether the email can be transmitted to the destination indicated by the destination information from the attribute information and the destination information, An e-mail terminal is caused to execute a transmission prohibiting step for prohibiting transmission of the e-mail to a destination determined to be impossible to transmit by a transmission enable / disable determining unit.

In this way, when the sender of the e-mail makes a mistake in the destination, the e-mail is not transmitted to the destination, so that it is possible to prevent leakage of confidential information due to an e-mail destination error.
Further, in the electronic mail terminal control program according to the present invention, the transmission prohibiting step deletes, from the electronic mail, an address associated with an address that is included in the electronic mail and is determined not to be transmitted. It is characterized by doing. In this way, when an e-mail destination error is detected, transmission of the e-mail to the destination can be efficiently prohibited.

  As described above, according to the present invention, it is possible to prevent disclosure of information to an inappropriate transmission partner only by a simple operation of setting attribute information of an e-mail when the user transmits the e-mail. Can do.

Hereinafter, embodiments of an electronic mail terminal according to the present invention will be described with an electronic mail system as an example with reference to the drawings.
[1] Configuration of E-Mail System FIG. 1 is a diagram showing a configuration of an e-mail system according to the present embodiment. As shown in FIG. 1, the e-mail system 1 has a configuration in which e-mail terminals 10 and 11 and an e-mail server 13 are connected via a communication network 12. The e-mail terminals 10 and 11 send and receive e-mail to and from each other via the e-mail server 13.

[2] Configuration of E-mail Terminal FIG. 2 is a diagram showing a functional configuration of the e-mail terminal 10 according to the present embodiment. Since the electronic mail terminal 11 has the same configuration as the electronic mail terminal 10, the description of the electronic mail terminal 10 is replaced with the description of the electronic mail terminal 11.
As shown in FIG. 2, the e-mail terminal 10 includes an e-mail creating unit 100, an e-mail attribute receiving unit 101, a transmission instruction receiving unit 102, an e-mail transmission processing unit 103, a destination address acquisition unit 104, transmission permission / inhibition A determination unit 105 and a transmission condition database 106 are provided.

The e-mail creation unit 100 is a functional block that creates an e-mail according to an instruction from the user of the e-mail terminal 10.
The email attribute accepting unit 101 is a functional block that accepts designation of attributes from the user of the email terminal 10 for each email created by the email creating unit 100. Here, the attribute of the e-mail is information for determining whether or not the e-mail can be transmitted for each destination, and is designated by the user who intends to transmit the e-mail according to the content of the e-mail.

The transmission instruction accepting unit 102 is a functional block that accepts a transmission instruction to send an email from the user of the email terminal 10. When receiving a transmission instruction from the user, the transmission instruction receiving unit 102 notifies the transmission permission determination unit 105 to that effect.
The e-mail transmission processing unit 103 is a functional block that executes a protocol process for transmitting an e-mail. In the present embodiment, an e-mail transmission process is executed with the e-mail server 13 in accordance with a POP3 (Post Office Protocol-version 3) procedure.

  The destination address acquisition unit 104 refers to all lines including destination information such as To lines and CC (Carbon Copy) lines included in the email header of the email created by the email creation unit 100. It is a functional block for acquiring an e-mail address that is the destination of the e-mail. In this case, the destination address acquisition unit 104 acquires all e-mail addresses that are destinations.

When receiving a notification that the transmission instruction has been received from the transmission instruction receiving unit 102, the transmission permission / inhibition determining unit 105 receives all the e-mail addresses that are the destinations of the e-mails related to the transmission instruction from the destination address acquiring unit 104. get. At the same time, the transmission permission / inhibition determining unit 105 acquires the attribute related to the email from the email attribute receiving unit 101.
Then, the transmission condition database is referred to using these electronic mail addresses and attributes as search keys, and it is determined whether or not the electronic mail can be transmitted for each electronic mail address. When an e-mail address determined not to be transmitted is detected, the transmission permission / inhibition determining unit 105 instructs the e-mail creating unit 100 to delete the e-mail address from the e-mail.

After determining whether or not transmission is possible for all electronic mail addresses, the transmission permission / non-permission determination unit 105 instructs the electronic mail transmission processing unit 103 to transmit the electronic mail.
The transmission condition database 106 is a database that stores transmission conditions indicating whether transmission is permitted or not permitted for each combination of an e-mail address and an attribute.
[3] Operation of E-mail Terminal 10 Next, the operation of the e-mail terminal 10 will be described. Since the e-mail terminal 11 operates in the same manner as the e-mail terminal 10, the description of the operation of the e-mail terminal 10 is replaced with the description of the operation of the e-mail terminal 11.

  FIG. 3 is a flowchart showing a flow of processing executed by the electronic mail terminal 10. As shown in FIG. 3, the e-mail terminal 10 first creates an e-mail according to the user's instruction by the e-mail creating unit 100 (step S100). Next, the e-mail terminal 10 receives the e-mail address of the created e-mail destination from the user (step S101). Further, the e-mail terminal 10 receives the e-mail attribute from the user by the e-mail attribute receiving unit 101 (step S102).

FIG. 4 is a diagram illustrating an e-mail creation window displayed when the e-mail terminal 10 creates an e-mail in accordance with a user instruction. As shown in FIG. 4, the e-mail creation window 2 includes text boxes 20 to 23 and a pull-down menu 24.
The e-mail terminal 10 receives the destination e-mail address of the e-mail in the text box 20. In this case, the e-mail terminal 10 may accept a plurality of destination e-mail addresses in the text box 20. In addition, the e-mail terminal 10 receives a destination e-mail address or the like to be described in the CC line of the e-mail header in the text box 21.

  The e-mail terminal 10 accepts input of a character string to be described in the Subject line of the e-mail header in the text box 22. In addition, the electronic mail terminal 10 accepts input of an electronic mail text in the text box 23. The body of the electronic mail may be in text format or in HTML (Hyper Text Markup Language) format. Although not particularly shown in FIG. 4, a file may be attached.

  The electronic mail terminal 10 accepts input of the attribute of the electronic mail through the pull-down menu 24. In the present embodiment, when the pull-down menu 24 is clicked, the e-mail terminal 10 displays each item of the menu such as “in-house”, “company A”, “company B”, “company C”, for example. Display a list. The e-mail terminal 10 receives the attribute selected by the user from the pull-down menu.

  Returning to FIG. 3, thereafter, the e-mail terminal 10 determines whether or not the transmission instruction receiving unit 102 has received a transmission instruction from the user. If the transmission instruction has not been accepted (step S103: NO), the processing as described above is continued. When a transmission instruction is received from the user (step S103: YES), the transmission condition determination unit 105 refers to the transmission condition database 106 in order to determine whether or not the electronic mail related to the transmission instruction can be transmitted (step S103). S104).

  If the transmission condition referred to is transmission permission (step S105: YES), an e-mail address that is a destination of the e-mail and that does not refer to the transmission condition related to the e-mail address is obtained. Judge whether there is. If it is determined that there is an unprocessed e-mail address (step S106: YES), the process proceeds to step S104 to refer to the transmission condition related to the e-mail address.

  When it is determined that there is no unprocessed e-mail address (step S106: NO), the e-mail terminal 10 transmits the e-mail to the e-mail transmission processing unit 103 by the transmission permission / inhibition determination unit 105. To instruct. When receiving the instruction, the e-mail transmission processing unit 103 transmits the e-mail according to the instruction to the e-mail server 13 (step S107).

  If the transmission condition cannot be transmitted with reference to the transmission condition database (step S105: NO), the transmission permission determination unit 105 deletes the email address from the email destination with respect to the email creation unit 100. (Step S108). In the present embodiment, even when the transmission condition corresponding to the e-mail address is not stored in the transmission condition database 106, an instruction is given to delete the e-mail address.

[3] Data Structure of Transmission Condition Database 106 Next, the data structure of the transmission condition database 106 will be described. FIG. 5 is a diagram illustrating a data structure of the transmission condition database 106. As shown in FIG. 5, the transmission condition database 106 has a tabular data structure in which attributes are arranged in the row direction and e-mail addresses are arranged in the column direction.

  In the present embodiment, the attributes that can be input by the user are “in-house”, “Company A”, “Company B”, and “Company C”. For example, when the transmission permission determination unit 105 specifies “dddd@shanai.co.jp” as an e-mail address and specifies “in-house” as an attribute and searches the transmission condition database 106, the transmission result is “permitted”. can get. When the e-mail address “ggggg@a-sha.co.jp” and the attribute “B” are designated, transmission “impossible” is obtained as a search result.

In the present embodiment, the users of the e-mail terminals 10 and 11 can freely add or delete the contents of the transmission condition database 106.
[4] Modifications Although the present invention has been described based on the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .

(1) In the above embodiment, the case where there are two e-mail terminals constituting the e-mail system 1 has been described as an example. However, it is needless to say that the present invention is not limited to this. Three or more electronic mail terminals may be configured.
Although not particularly mentioned in the above embodiment, the e-mail terminal may be a so-called personal computer or a mobile terminal such as a mobile phone. In addition, as long as it is a device having a function of creating and sending an e-mail regardless of the model, the present invention can be applied to obtain the effect. In addition, the present invention does not depend on the model of the e-mail server, and can provide an effect regardless of the protocol used between the e-mail terminal and the e-mail server.

  Although not particularly mentioned in the above embodiment, the communication network 12 may be a so-called LAN (Local Area Network) or a WAN (Wide Area Network). Moreover, it may be a private network used in a specific company or the like, or may include a communication network such as the Internet used by an unspecified person. Furthermore, the communication network may be a wired network or a wireless network. These may be used in combination.

(2) In the above embodiment, it is determined whether or not transmission is possible by referring to all lines including destination information such as To lines and CC lines included in the e-mail header. Needless to say, the following may be used instead.
That is, it may be determined whether or not transmission is possible with reference to only a specific line included in the e-mail header. For example, only the To line may be referred to, or only the BCC line may be referred to. In this way, even for a destination that is not permitted to be transmitted by the attribute specified by the user who transmits the e-mail, the e-mail address related to the destination is set in a row that is not referred to for determining whether or not transmission is possible. The electronic mail can be transmitted by describing. Therefore, there is no need to separately send an e-mail having the same contents to the destination, so that it is possible to improve the convenience of the e-mail without the user's trouble.

(3) Although not particularly mentioned in the above embodiment, the present invention does not preclude taking other security measures for the e-mail. For example, the above-described digital signature may be applied together. . In addition, other security measures may be taken. The present invention can achieve the effect regardless of the security measures.
Further, in the above embodiment, when the transmission condition database is searched and the corresponding transmission condition is not obtained, the destination e-mail address is deleted from the e-mail, but instead, as follows. Also good.

  That is, an e-mail may be transmitted by taking a predetermined security measure for an e-mail address for which the transmission condition database has not been obtained by searching the transmission condition database. For example, an e-mail to be sent to an e-mail address for which no transmission condition has been obtained may be encrypted, and an electronic certificate may be used so that only a specific recipient can open the e-mail or attached file. . In this way, a certain level of security can be protected even for e-mail destinations that were not assumed in advance.

(4) In the above embodiment, the e-mail terminal determines whether e-mail can be transmitted. Alternatively, the e-mail server may determine whether e-mail can be transmitted.
FIG. 6 is a functional configuration diagram showing a functional configuration of the electronic mail terminal according to the present modification. As shown in FIG. 6, the e-mail terminal 20 includes an e-mail creation unit 200, an e-mail attribute reception unit 201, a transmission instruction reception unit 202, and a transmission processing unit 203.

  The e-mail creation unit 200 is a functional block that creates an e-mail according to an instruction from the user of the e-mail terminal 20. The e-mail attribute accepting unit 201 is a functional block that accepts input of attribute information for determining whether or not e-mail can be transmitted. When receiving an instruction to send an e-mail from the user, the transmission instruction accepting unit 202 causes the e-mail creating unit 200 to attach the attribute information to the e-mail, and then sends the e-mail to the e-mail transmission processing unit 203. This is a functional block to be transmitted. The e-mail transmission processing unit 203 is a functional block that transmits an e-mail in accordance with an instruction from the transmission instruction receiving unit 202.

FIG. 7 is a functional configuration diagram showing a functional configuration of the electronic mail server according to this modification. As shown in FIG. 7, the e-mail server 23 includes an e-mail receiving unit 230, an e-mail attribute acquisition unit 231, an e-mail transmission processing unit 232, a destination address acquisition unit 233, a transmission availability determination unit 234, and a transmission condition database 235. It has.
The e-mail receiving unit 230 is a functional block that receives an e-mail from an e-mail terminal according to a predetermined procedure. The e-mail attribute acquisition unit 231 is a functional block that acquires attribute information attached to the e-mail received by the e-mail receiving unit 230. The e-mail transmission processing unit 232 is a functional block that transmits an e-mail according to an instruction from the transmission permission / inhibition determining unit 234. The destination address acquisition unit 233 is a functional block that acquires a destination email address included in the email header of the email received by the email receiver 230.

  The transmission permission / inhibition determination unit 234 receives the e-mail address of the e-mail received by the e-mail receiving unit 230, the attribute information acquired by the e-mail attribute acquisition unit 231, and the e-mail acquired by the destination address acquisition unit 233. This is a functional block that searches the transmission condition database 235 using a mail address and determines whether or not an electronic mail can be transmitted. The transmission permission / inhibition determination unit 234 instructs the email transmission processing unit 232 to delete the email address whose transmission condition is disabled from the transmission destination of the email. In addition, the transmission permission / inhibition determination unit 234 instructs the email transmission processing unit 232 to transmit the email after finishing the search of the transmission condition for all the destination email addresses included in the email. .

  The transmission condition database 235 is a database that stores transmission conditions specified by an e-mail source e-mail address, a destination e-mail address of the e-mail, and attribute information of the e-mail. FIG. 8 is a diagram illustrating the data structure of the transmission condition database 235. As shown in FIG. 8, for example, the source email address of the email is “dddd@shanai.co.jp”, the destination email address is “eeee@shanai.co.jp”, and the attribute is “internal” ", The transmission condition is" permitted "for transmission.

As mentioned above, even if it takes a structure like this modification, the effect of the present invention can be acquired.
Note that the data structure of the transmission database 235 described above is merely an example, and instead of the above, a data structure as illustrated in FIG. 5 may be used. In this case, the transmission condition cannot be set for each sender of the e-mail, but the data amount of the transmission condition database can be greatly reduced. Therefore, when the e-mail server 23 receives e-mails from a large number of e-mail terminals, it is extremely effective as a means for reducing the storage area required for the e-mail server 23 to store the transmission condition database.

  In this way, it is possible to collectively manage transmission conditions in the case of managing the security of e-mails within one company. Therefore, it is possible to reduce the labor required for maintenance of the transmission condition database, and it is possible to reduce work errors caused by the work, thereby realizing higher security at a lower cost.

(5) In the above embodiment, the e-mail is not transmitted to a destination that cannot be transmitted with reference to the transmission condition database. In addition, the following may be performed.
That is, the e-mail terminal may present a list of e-mail addresses excluded from e-mail destinations to the user before sending the e-mail to the e-mail server. In this way, when the user mistakenly inputs the destination electronic mail address, an opportunity to correct it can be given, so that the electronic mail can be transmitted to a more accurate destination.

(6) In the above embodiment, the case where the electronic mail terminal accepts only one piece of attribute information from the user has been described. However, it goes without saying that the present invention is not limited to this, and the following may be used instead. good.
That is, the e-mail terminal may accept a plurality of attribute information from the user. In this case, the transmission permission / inhibition determining unit 105 obtains the number of transmission conditions equal to the number of attributes for one destination email address from the transmission condition database 106. The transmission permission / inhibition determination unit 105 deletes the destination email address from the email if all the acquired transmission conditions are not transmittable, and does not delete the email address otherwise.

In this way, an electronic mail having the same content can be transmitted to a wider range of destinations with less effort, which can contribute to user convenience.
Alternatively, the transmission permission determination unit 105 deletes the destination e-mail address from the e-mail if any of the acquired transmission conditions is not transmittable, otherwise the e-mail address is determined. You may not delete it. In this way, a stricter security check can be realized, so that higher confidentiality can be maintained.

  (7) In the above embodiment, the e-mail terminal to which the present invention is applied has been described. However, it goes without saying that the present invention is not limited to this, and the processing described in the above embodiment is performed by a computer. It may be an e-mail terminal control program to be executed. The present invention may also be an e-mail terminal control method executed by a computer in accordance with such an e-mail terminal control program. Furthermore, the present invention should be construed to include a computer-readable recording medium storing the electronic mail terminal control program within its technical scope.

  (8) In the above embodiment, “in-house”, “Company A”, “Company B” and “Company C” have been described as attribute information. However, it goes without saying that the present invention is not limited to this. Other information may be attribute information. For example, in a school, "teacher", "first grader", "second grader", "1 set", "2 set", etc. may be used as attribute information. What information should be used as attribute information should be determined exclusively according to the needs of the user, and the present invention can exert its effect regardless of what information is used as attribute information.

  The electronic mail terminal and the electronic mail system according to the present invention are useful as a technique for preventing leakage of confidential information due to an erroneous destination of electronic mail.

It is a figure which shows the structure of the electronic mail system which concerns on embodiment of this invention. It is a figure which shows the function structure of the electronic mail terminal 10 which concerns on embodiment of this invention. It is a flowchart which shows the flow of the process which the electronic mail terminal 10 which concerns on embodiment of this invention performs. It is a figure which illustrates the email creation window displayed when the email terminal 10 which concerns on this Embodiment produces an email according to a user's instruction | indication. It is a figure which shows the data structure of the transmission condition database 106 which concerns on embodiment of this invention. It is a functional block diagram which shows the function structure of the electronic mail terminal which concerns on the modification (4) of this invention. It is a functional block diagram which shows the function structure of the electronic mail server which concerns on the modification (4) of this invention. It is a figure which shows the data structure of the transmission condition database 235 which concerns on the modification (4) of this invention.

Explanation of symbols

1 ……………………………… E-mail system 10, 11, 20 ………… E-mail terminal 12 ………………………… Communication network 13, 23 ………………… E-mail server 100, 200 ......... E-mail creation unit 101, 201 ......... E-mail attribute receiving unit 102, 202 ......... Sending instruction receiving unit 103, 203, 232 ... E-mail transmission processing Sections 104, 233 ... Destination address acquisition sections 105, 234 ... Transmission permission determination section 106, 235 ... Transmission condition database 230 ... E-mail reception section 231 ………………………… Email attribute acquisition section

Claims (10)

An email terminal for sending emails,
Attribute information acquisition means for acquiring attribute information related to the e-mail;
Destination information acquisition means for acquiring destination information of the e-mail;
From the attribute information and the destination information, transmission permission determination means for determining whether the electronic mail can be transmitted to a destination indicated by the destination information;
An e-mail terminal comprising: a transmission prohibiting unit that prohibits transmission of the e-mail to a destination that is determined to be unsuccessful by the transmission permission determining unit. 2. The electronic device according to claim 1, wherein the transmission prohibiting unit deletes, from the electronic mail, a destination address that is a destination address included in the electronic mail and is related to a destination that is determined to be non-transmissible. Mail terminal. A transmission permission / inhibition storage means for storing the permission / inhibition of transmission of an e-mail in association with the attribute information and the destination information;
2. The electronic mail according to claim 1, wherein the transmission permission / non-permission determining unit determines whether the electronic mail can be transmitted by referring to the transmission / non-transmission possibility stored in the transmission permission / non-transmission storing unit. Terminal. Provided with electronic certificate sending means for attaching an electronic certificate to an e-mail and sending it,
The transmission permission / inhibition determining means relates to the transmission information with electronic certificate when the transmission permission / inhibition storage means does not store the permission of transmission associated with the attribute information and the destination information. The electronic mail terminal according to claim 3, wherein the electronic mail is transmitted to a destination. An e-mail system comprising an e-mail terminal that transmits e-mail and an e-mail server that transfers the e-mail,
The e-mail terminal is
Attribute information acquisition means for acquiring attribute information related to the e-mail;
Email sending means for sending the email to the email server;
Attribute information transmission means for associating the attribute information with the email and transmitting the email to the email server;
The email server is
E-mail receiving means for receiving e-mail from the e-mail terminal;
Attribute information receiving means for receiving attribute information associated with the e-mail;
Destination information acquisition means for acquiring destination information of the e-mail;
From the attribute information and the destination information, transmission permission determination means for determining whether the electronic mail can be transmitted to a destination indicated by the destination information;
An e-mail system comprising: a transmission prohibiting unit that prohibits transmission of the e-mail to a destination determined to be unsuccessful by the transmission permission determining unit. 6. The electronic mail according to claim 5, wherein the transmission prohibiting unit deletes, from the electronic mail, a destination address that is a destination address included in the electronic mail and that is related to a destination that is determined to be non-transmissible. Mail system. The e-mail server includes transmission availability storage means for storing e-mail transmission in association with the attribute information and the destination information,
6. The electronic mail according to claim 5, wherein the transmission permission determination unit determines whether the transmission of the electronic mail is possible by referring to the transmission permission stored in the transmission permission storage unit. system. The e-mail server includes a sending unit with an electronic certificate for sending an e-mail with an electronic certificate attached thereto,
The transmission permission / inhibition determining means relates to the transmission information with electronic certificate when the transmission permission / inhibition storage means does not store the permission of transmission associated with the attribute information and the destination information. The electronic mail system according to claim 7, wherein the electronic mail is transmitted to a destination. An e-mail terminal control program executed by an e-mail terminal that transmits e-mail,
An attribute information acquisition step of acquiring attribute information related to the email;
A destination information acquisition step of acquiring destination information of the e-mail;
From the attribute information and the destination information, a transmission permission / inhibition determining step for determining whether the electronic mail can be transmitted to a destination indicated in the destination information;
An e-mail terminal control program that causes an e-mail terminal to execute a transmission prohibiting step for prohibiting transmission of the e-mail to a destination that is determined to be unsuccessful by the transmission enable / disable determining means. 10. The electronic mail according to claim 9, wherein the transmission prohibiting step deletes, from the electronic mail, a destination address that is a destination address included in the electronic mail and that is related to an address that is determined not to be transmitted. Mail terminal control program.

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