JP2000022739A - Electronic mail system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the leakage of information by preventing erroneous delivery of electronic mails in an electronic mail system. SOLUTION: This electronic mail system is provided with a sever computer 1 and a client computer 2 connecting to the server computer 1, and the server computer sends an electronic mail from the client computer. The server computer is provided with a mail transfer filter 12 and a message transfer agent 11, and the mail transfer filter checks a set of a preset transmission source and a preset destination upon the receipt of a transmission request of an electronic mail and discriminates a transmission enable state of the electronic mail when a pair of a request transmission source and a request destination denoted in the transmission request is in existence in the set above. When the transmission is enabled, the message transfer agent transfers an electronic mail depending on the transmission request.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic mail system, and more particularly, to an electronic mail system capable of preventing erroneous transmission of an electronic mail.

[0002]

2. Description of the Related Art Conventionally, as an electronic mail system, for example, an electronic mail system disclosed in Japanese Patent Application Laid-Open No. Hei 9-200256 is known. In this e-mail system, a destination error is notified to the e-mail user at an early stage, and even if the e-mail address is uncertain, the e-mail is accurately sent to the person to whom the e-mail is to be sent. Is input, the address is transmitted as a client request to the mail server to which the client belongs. The server searches the address database to determine whether the mail user includes the destination mail address received in the client request. If the outgoing mail address does not exist in the address database, the server searches the temporary address database.
When a mail address can be retrieved by these two retrieval operations, a response between the client and the server is communicated to the mail client, and a mail user is notified of the presence of the mail address.

As described above, in the conventional e-mail system, in order to prevent erroneous transmission of e-mail, the mail server searches the address database according to the address from the client and uses the mail to confirm the existence of the e-mail address. To notify the person.

[0004]

By the way, in the conventional e-mail system, the mail server does not manage the addresses of both the transmission destination and the transmission source. Therefore, for example, when an error occurs in the address description, In some cases, an e-mail may be sent to a different address. In other words, in the conventional e-mail system, when there is an error in the address description, the e-mail may be sent to another address (destination), and as a result, the other party who does not want to know the contents of the e-mail May be sent an e-mail.

As described above, the conventional electronic mail system has a problem that it is difficult to prevent erroneous transmission of electronic mail.

An object of the present invention is to provide an electronic mail system capable of preventing erroneous transmission of electronic mail and preventing information leakage.

[0007]

According to the present invention, there is provided a server computer and a client computer connected to the server computer, wherein the server computer transmits an e-mail from the client computer. In the electronic mail system, when the server computer receives the electronic mail transmission request, the server computer checks a set of a transmission source and a transmission destination set in advance, and determines a request transmission source and a request transmission destination indicated by the transmission request. An electronic device comprising: a mail transfer filter that enables transmission when a pair exists in the set; and a message transfer agent that transfers the electronic mail in response to the transmission request when transmission is possible. A mail system is obtained.

[0008] For example, the server computer is provided with a transmittable domain list in which the source and destination pairs are registered as a source-destination domain name pair. When the domain of the address of the transmission destination is registered in the transmittable domain list, the transmission request is passed to the second means.

Further, the server computer is provided with a transmittable address list in which the source and destination pairs are registered as a source-destination address name pair. If the domain of the destination address is not registered in the transmittable domain list, it is further checked whether the destination address is registered in the transmittable address list, and the destination address is If registered in the list of available addresses, the mail transfer filter passes the transmission request to the message transfer agent.

[0010] In addition, if the destination address is not registered in the transmittable address list, the mail transfer filter responds to the client computer that transmission is impossible.

In the server computer, a receiving domain work list in which a domain of an external source address of an e-mail sent from the outside to the server computer is registered together with a destination address, or the external source address may be the destination. It may include a receiving address work list registered with the address, in which case the mail transfer filter determines whether the destination address is registered in the receiving domain work list or the receiving address work list. If checked and registered, the mail transfer filter passes the transmission request to the message transfer agent, and if not registered, the mail transfer filter responds to the client computer that transmission is impossible.

[0012] When the client computer, which is the receiving destination, makes a request to send the mail with the external source as a destination, the mail transfer filter automatically sets the sendable domain list or the sendable address list. May be additionally registered.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, the illustrated e-mail system includes a server computer 1 and a client computer 2, and the server computer 1 and the client computer 2 are connected by a communication line 3. As shown in the figure, the server computer 1 has a message transfer agent 11 and a mail transfer filter 1.
The mail transfer filter 12 is connected to a log file 4a. The log file 4 stores a transmittable domain list 13, a transmittable address list 14, a receive domain work list 15, and a receive address work list 16. On the other hand, the client computer 2 is provided with a user agent 17.

The user agent 17 requests the message transfer agent 11 to send an e-mail created by the client computer 2 to a transmission address. The mail transfer filter 12 intercepts a request from the user agent 17 to the message transfer agent 11 and, as described later, a sendable domain list 13, a sendable address list 14, a receiving domain work list 15, and a receiving address work list. The request is checked with reference to FIG. If the request is valid, the mail transfer filter 12 passes the request to the message transfer agent 11, while if not, the mail transfer filter 12 notifies the user agent 17 of an error. The message transfer agent 11 transfers the e-mail transmitted from the client computer 2 to the transmission address as described later.

Here, referring to FIGS. 1 and 2, as described above, the server computer 1 has the transmittable domain list 13, the transmittable address list 14, the receive domain work list 15, and the receive address work list. 1
There are six.

As shown in FIG. 2A, the transmittable domain list 13 includes a plurality of records. Each record includes a source (address or domain name), a destination domain name, and a last update date. Consists of fields. The source and destination domain names can also be described using regular expressions.

As shown in FIG. 2B, the transmittable address list 14 includes a plurality of records. Each record includes a source (address or domain name), a destination address name, and a last update date field. It is composed of

As shown in FIG. 2C, the receiving domain work list 15 has a plurality of records, and each record is composed of fields of a destination address, a source domain name, and a last update date. .

As shown in FIG. 2D, the received address work list 16 has a plurality of records, and each record is composed of fields of a destination address, a source address name, and a last update date. .

The transmittable domain list 13 and the transmittable address list 14 are managed by the mail transfer filter 12, and are managed manually or automatically when the transmittable domain list 13 and the transmittable address list 14 are managed. You. When manually managing, the administrator of the server computer 1 operates the mail transfer filter 12 to add or modify a domain name or an address name,
Add or update records. On the other hand, when automatically managing the mail, the mail transfer filter 12 stores the source address or the domain of the mail transmitted to the server computer 1 together with the destination address on the reception domain work list 15 or the reception address work list 16. Register for a predetermined period. Then, when the recipient makes an e-mail transmission request to the transmission destination domain or address during registration in the reception domain work list 15 or the reception address work list 16, the mail transfer filter 12 automatically transmits the transmission possible domain list 13 or transmission. Additional registration is made in the possible address list 14. Whether to perform automatic management is determined by the setting of the mail transfer filter 12.

Referring to FIG. 1, the message transfer agent 11 is operating in the server computer 1 as described above. In the transmittable domain list 13 and the transmittable address list 14, in consideration of prevention of information leakage, each address under the management of the e-mail system is set as a transmission source, and a destination address or domain that can be transmitted from each address is registered. ing. The mail transfer filter 12 includes a sendable domain list 13, a sendable address list 14, a receiving domain work list 15,
And / or checks that a set of source and destination addresses or domains is registered in the reception address work list 16 and passes an e-mail transmission request to the message transfer agent 11.

Referring to FIGS. 1, 3 and 4, the illustrated e-mail system will be described in detail.

When transmitting an e-mail from the client computer 2, first, the user agent 17 transmits the e-mail to the message transfer agent 11 of the server computer 1.
Is notified of the address of the recipient (transmission destination) (step S1). At this time, the mail transfer filter 12 intercepts this notification to the message transfer agent 11 (step S2) and checks whether the domain of the address of the recipient is registered in the transmittable domain list 13 (step S3). ). If the above domain is registered in the transmittable domain list 13 (step S
4), the mail transfer filter 12 passes the notification from the user agent 17 to the message transfer agent 11 (Step S5).

On the other hand, if the domain is not registered in the transmittable domain list 13 in step S 4, the mail transfer filter 12 further checks the transmittable address list 14 and sets the recipient's address in the transmittable address list 14. It is checked whether or not it is registered in (step S6). If the address of the recipient is registered in the transmittable address list 14 (step S7), the process proceeds to step S5, as described above, and the mail transfer filter 12 sends the notification from the user agent 17 to the message transfer agent 11 Pass to.

In step S7, if the address of the recipient is not registered in the transmittable address list 14,
If automatic registration has been set (step S
8), the mail transfer filter 12 checks the reception domain work list 15 or the reception address work list 16 and checks whether or not the address of the recipient is registered (step S9). If the address of the recipient is registered (step S10), the mail transfer filter 12 adds a new record to the transmittable domain list 13 or the transmittable address list 14 (step S11).
Thereafter, the mail transfer filter 12 proceeds to step S5, and passes the request (notification) from the user agent 17 to the message transfer agent 11.

In step S 10, when the address of the recipient does not exist in the receiving domain work list 15 or the receiving address work list 16, the mail transfer filter 12 sends a response indicating that transmission is impossible in place of the message transfer agent 11. It returns to the user agent 17 (step S12). Then, the mail transfer filter 12
Records in the log file 4 a record of the sender and the recipient who was unable to send, together with the time of occurrence (step S1).
3). Thereafter, the record of the recipient who was unable to transmit is notified to the sender by e-mail (step S14).

[0028]

As described above, according to the present invention, when an e-mail is sent, the mail transfer filter checks the sender address and the receiver address, that is, the mail transfer filter double-checks. Therefore, even if there is an error in the address description, the e-mail is hardly transmitted to another address (destination), and there is an effect that erroneous transmission of the e-mail can be prevented.

Further, in the present invention, as described above, the e-mail is transmitted after the sender address and the recipient address are checked by the mail transfer filter.
Unnecessary transmission of e-mail is prohibited, so that network congestion can be alleviated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an electronic mail system according to the present invention.

2A is a diagram showing a list stored in a log file shown in FIG. 1, FIG. 2A is a diagram showing a transmittable domain list, FIG. 2B is a diagram showing a transmittable address list, and FIG.
FIG. 6 is a diagram showing a reception domain work list, and FIG.

FIG. 3 is a flowchart for explaining the operation of the electronic mail system shown in FIG. 1;

FIG. 4 is a flowchart for explaining the operation of the electronic mail system shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Server computer 2 Client computer 3 Communication line 4 Log file 11 Message transfer agent 12 Mail transfer filter 13 Sendable domain list 14 Sendable address list 15 Receive domain work list 16 Receive address work list 17 User agent

Claims (6)

[Claims] 1. An electronic mail system comprising a server computer and a client computer connected to the server computer, wherein the server computer transmits an electronic mail from the client computer. When a request for transmission of the e-mail is received, a set of a transmission source and a transmission destination set in advance is checked, and if a pair of a request transmission source and a transmission destination indicated by the transmission request exists in the pair, the transmission is performed. An electronic mail system, comprising: first means for enabling transmission; and second means for transferring the electronic mail in response to the transmission request when transmission is possible. 2. The e-mail system according to claim 1, wherein the server computer has a sendable domain list in which the source and destination pairs are registered as a source-destination domain name pair. Wherein the first means is provided when the domain of the address of the destination is registered in the list of transmittable domains,
An electronic mail system wherein the transmission request is passed to the second means. 3. The e-mail system according to claim 2, wherein the server computer has a transmittable address list in which the source and destination pairs are registered as a source-destination address name pair. Wherein the first means is that the domain of the address of the destination is not registered in the list of available domains,
Further, it is checked whether or not the destination address is registered in the transmittable address list. If the destination address is registered in the transmittable address list, the first unit performs the transmission. An electronic mail system, wherein a request is passed to said second means. 4. The electronic mail system according to claim 3, wherein if the destination address is not registered in the transmittable address list, the first means disables transmission to the client computer. An e-mail system characterized by responding. 5. An e-mail system according to claim 3, wherein a domain of an external source address of the e-mail sent from the outside to the server computer is registered in the server computer together with a destination address. A work list or a reception address work list in which the external source address is registered together with the reception address is provided, and the first means is configured such that the transmission destination address is in the reception domain work list or the reception address work list. The first means passes the transmission request to the second means if it has been registered by checking whether it has been registered or not, and if not registered, the first means sends the request to the client computer. An e-mail system characterized by responding that transmission is impossible. 6. The electronic mail system according to claim 5, wherein when the client computer, which is the reception destination, requests transmission of the mail with the external transmission source as a transmission destination, the first means: An e-mail system, wherein additional registration is performed in the transmittable domain list or the transmittable address list.