JP2011082733A - Electronic mail system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic mail system which does not erroneously detect proper e-mail as nuisance e-mail without increasing operation loads for transmitting e-mail through e-mail addresses of a plurality of domain names. <P>SOLUTION: A e-mail server 306 which transmits the e-mail using different domain names to an external e-mail server is provided with: an e-mail delivery control 403 which controls delivery of the e-mail; network interfaces 406, 407 which correspond to the domain names one to one; an e-mail relay 405 which receives the e-mail delivered from the e-mail delivery control 403, and transmits the received e-mail from the network interface 406; and a domain list data base 404 which stores information for specifying the e-mail relay 405 by being associated with the domain names. The e-mail delivery control 403 automatically sorts the e-mail so that the e-mail is transmitted from the different network interfaces 406, 407, respectively according to the domain names of the e-mail. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic mail system.

  Currently, electronic mail systems are widely used as one of basic services on the Internet, and are established in various organizations and services.

  For example, one organization may have multiple domain name email addresses for each affiliated or related group company or for each service deployed in multiple countries. Therefore, each organization needs to construct an e-mail system that can process e-mail addresses of a plurality of domains owned by one e-mail system for the purpose of reducing construction cost and operation load.

  On the other hand, when using e-mail, there is a problem of so-called “spam” that is sent indiscriminately and in large quantities regardless of the recipient's intention. It is indispensable.

  As an example of this measure, a mechanism having the following configuration has been proposed. That is, first, in the mail server that receives the e-mail, the DNS server is inquired about the IP address of the mail server that has transmitted the e-mail. The domain name of the host name thus obtained is compared with the domain name of the sender mail address of the sent e-mail. As a result, when the domain names do not match, it is determined that the spam mail is going to be sent by an illegal mail transfer process, and the reception of the electronic mail is rejected (see, for example, Patent Document 1).

  In this measure, one mail server that sends e-mails sends only e-mails that have only one domain name as the sender's e-mail address and sends e-mails that have multiple domain names as the sender's e-mail addresses. There is a difference in the effect that can be obtained.

  That is, when one mail server that sends an e-mail only sends an e-mail that has only one domain name as the sender e-mail address, the IP address of the e-mail server that sends the e-mail and the domain name of the sender e-mail address Corresponds one-to-one. Therefore, the DNS server search result is uniquely determined, and no problem occurs even if the above-described spam mail countermeasure is implemented.

  On the other hand, when one mail server that sends an e-mail sends an e-mail with a plurality of domain names as sender mail addresses, the IP address of the mail server that sends the e-mail and the domain name of the sender mail address are There is no one-to-one correspondence. For this reason, the DNS server search result is not uniquely determined, and the domain name of the sender email address does not match the host name of the mail server that sends the email, so that the email is not spam. Regardless, it may be determined to be spam. In this case, the mail server that receives the electronic mail refuses to receive the electronic mail.

JP 2007-317005 A

  As a method of avoiding the above problem, a method of switching a network interface so as to prepare a plurality of transmission IP addresses corresponding to the number of domains of the transmission mail address and to uniquely associate them can be considered. As a method of switching the network interface, there is a method of executing as many mail server processes as the number of source domain names on one mail server.

  However, in this method, it is necessary to prepare not only for sending but also for receiving IP addresses as many as the number of source domain names, and to switch the IP address to be transferred according to the source domain name in another terminal or mail server. is there.

  In this case, not only transmission distribution processing other than other terminals or mail servers is required, but a data storage spool directory, management commands, and the like must be prepared for each process. In addition, there is a problem that the operational load is remarkably increased, for example, it is necessary to individually set the monitoring of the operation state. Since the number of processes to be operated increases as the number of domains handled increases, operation management becomes more difficult.

  An object of the present invention is to prevent erroneous detection of spam mail without increasing operational load when one electronic mail system transmits electronic mail using mail addresses of a plurality of domain names. It is to provide an e-mail system.

  In order to achieve the above object, an electronic mail system according to the present invention uses n (n is an integer of 2 or more) different domain names as its own domain, and uses each mail address of the n domain names. An electronic mail system including a mail server for transmission that transmits mail to an external mail server, wherein the mail server includes a mail delivery control unit that controls delivery of the electronic mail, and 1 for each of the n domain names. A physical or virtual network interface corresponding to each other having at least n different IP addresses, and a network interface for receiving an electronic mail delivered from the mail delivery control unit, at least n-1 network interfaces out of n network interfaces; Identify at least n-1 mail relay units that transmit the received electronic mail to the external mail server via the corresponding network interface and the at least n-1 mail relay units. A storage unit that stores information to be associated with a corresponding domain name, and the mail delivery control unit includes information on the mail relay unit corresponding to a domain name of an email to be transmitted to the external mail server Is stored in the storage unit, and the electronic mail is transmitted to the mail relay unit corresponding to the domain name of the electronic mail.

  According to the present invention, when one e-mail system transmits an e-mail using e-mail addresses of a plurality of domain names, it is possible to prevent erroneous detection of spam mail without increasing the operation load. Can be.

It is a figure which shows schematic structure of the information processing apparatus with which the mail server program and mail relay program which are used for the electronic mail system which concerns on embodiment of this invention are performed. It is a figure which shows schematic structure of the electronic mail system which concerns on embodiment of this invention. It is a figure which shows schematic structure of the mail server [main] shown by FIG. It is a figure which shows schematic structure of the domain database shown by FIG. It is a flowchart which shows the process of the mail delivery control part in the mail server [main] shown by FIG. 6 is a flowchart showing a process of a mail relay unit (details of the process in step S608 shown in FIG. 5) in the mail server [main] shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a case where the present invention is applied to processing when the mail server transmits an electronic mail to another mail server on the Internet will be described.

  FIG. 1 is a diagram showing a schematic configuration of an information processing apparatus that executes a mail server program and a mail relay program used in an electronic mail system according to an embodiment of the present invention.

  The information processing apparatus 200 includes a CPU 201, a BMU 202, a ROM 203, a RAM 204, an HDD 205, a removable disk drive 206, and one or a plurality of network interfaces 207. Hereinafter, “one or more network interfaces 207” will be simply referred to as “network interfaces 207”.

  The CPU 201 controls various devices constituting the information processing apparatus 200 based on a control program stored in the ROM 203, HDD 205, or removable disk drive 206.

  The BMU (bit move unit) 202 is, for example, data transfer between memories (for example, between the RAM 204 and a VRAM 213 described later), and data transfer between the memory and each I / O device (for example, the network interface 207). To control.

  The ROM 203 stores various control programs and data. The RAM 204 functions as a work area for the CPU 201, a data save area during error processing, a control program load area, and the like.

  The HDD 205 stores each control program and content executed in the information processing apparatus 200. For example, the HDD 205 stores a mail server program, a mail relay program, temporarily stored e-mail data to be transmitted / received, a domain list database to be referred to during e-mail delivery control, and the like.

  The removable disk drive 206 controls access to a removable disk represented by a CD-ROM or the like. The network interface 207 is connected to a communication line 208 connected to the network. The network interface 207 communicates with other information processing apparatuses connected to the network via the communication line 208.

  The information processing apparatus 200 includes a CPU bus 215 that connects various devices constituting the information processing apparatus 200. The CPU bus 215 includes an address bus, a data bus, and a control bus.

  The provision of the control program to the CPU 201 can be performed from the ROM 203, the HDD 205, and the removable disk drive 206, or can be performed from another information processing apparatus or the like via the network interface 207 and the communication line 208.

  The information processing apparatus 200 includes a keyboard interface 209, a pointing device interface 211, and a VRAM 213 as input / output devices. A keyboard 210, a pointing device 212, and a display 214 can be connected to the keyboard interface 209, the pointing device interface 211, and the VRAM 213, respectively.

  The keyboard 210 has various keys for inputting characters, and transmits input data through the keyboard interface 209. The pointing device 212 performs instructions and operations such as icons and menus displayed on the display 214 via the pointing device interface 211. Using these input / output devices, operations and settings for the information processing apparatus 200 are performed.

  The first control program executed by the CPU 201 is an application management control program that manages a plurality of application programs.

  In accordance with the application management control program, the CPU 201 performs memory management of the application by combining the RAM 204 and the HDD 205 in accordance with the memory request from the application under management.

  Further, the CPU 201 controls access to the HDD 205, the removable disk drive 206, and the network interface 207 from the application under management according to the application management control program.

  Further, the CPU 201 may set an IP address to the network interface according to the application management control program and provide a plurality of virtual network interfaces. In the following description, it is assumed that the application management control program is an operating system (hereinafter referred to as “OS”).

  The second control program executed by the CPU 201 is an application program that runs on the OS. The CPU 201 performs processing instructed by an application program operating on the OS instructed by the OS. Hereinafter, the application program is described as a mail server program and a mail relay program.

  The electronic mail system according to the present invention is constructed using the information processing apparatus 200 as a mail server. Hereinafter, the “information processing apparatus” is referred to as “mail server”.

  FIG. 2 is a diagram showing a schematic configuration of the electronic mail system according to the embodiment of the present invention.

  The server system 308 is an e-mail transmission source and includes n (n is an integer of 2 or more) terminals or application servers. Here, it is assumed that n = 2 and two terminals or application servers 301 and 302 (hereinafter referred to as “application servers 301 and 302”) are connected to the LAN 305 in the server system 308.

  Each of the application servers 301 and 302 uses a different domain name as its own domain. Therefore, e-mails having different sender mail address domain names are transmitted from the application servers 301 and 302 to the mail server 306 for transmission connected to the LAN 305 in the server system 308, respectively. Here, it is assumed that e-mails having domain names “domain A” and “domain B” of the sender mail address are transmitted from the application servers 301 and 302, respectively.

  The mail server 306 transmits an e-mail to the mail servers 310 and 315 of other server systems 314 and 319 via the Internet 309. The mail servers 310 and 315 function as received mail servers.

  In the server system 314, the mail server 310 is connected to a LAN 313 in the server system 314, and a plurality of terminals or application servers 311 and 312 are connected to the LAN 313. In the server system 319, the mail server 315 is connected to a LAN 318 in the server system 319, and a plurality of terminals or application servers 316 and 317 are connected to the LAN 318.

  FIG. 3 is a diagram showing a schematic configuration of the mail server 306 shown in FIG.

  The mail server 306 includes the same number of network interfaces 406 and 407 as the plurality of transmission source domains transmitted from the mail server 306.

  Each of the network interfaces 406 and 407 includes one or a plurality of physical network interfaces and communication lines, and includes a virtual network interface that the CPU 201 performs processing according to an instruction from the OS.

  The CPU 201 assigns different IP addresses to the network interfaces 406 and 407 in accordance with instructions from the OS. In FIG. 3, “xxx.xxx.xxx.AAA” is shown as the IP address of the network interface 406, and “xxx.xxx.xxx.BBB” is shown as the IP address of the network interface 407.

  The mail server 306 includes a mail processing unit 402 in which the CPU 201 processes electronic mail in accordance with instructions from the mail server program. The mail processing unit 402 receives e-mails transmitted from the application servers 301 and 302.

  In the mail processing unit 402, the CPU 201 performs processing such as mail address conversion by an alias database, temporary storage of email in a mail queue, storage of email in a personal user's mailbox, etc., according to instructions of the mail server program. I do. Since these processes can use known general processes, a detailed description thereof is omitted here.

  The mail processing unit 402 includes a mail delivery control unit 403. In the mail delivery control unit 403, the CPU 201 analyzes the header information of the email according to the instruction of the mail server program, and performs a process of distributing the email according to the mail delivery means specified by the mail server program.

  The mail processing unit 402 and the network interface 407 are made to correspond one-to-one. The CPU 201 transmits all electronic mails to be transmitted directly from the mail delivery control unit 403 to an external mail server via the network interface 407.

  The mail server 306 has a mail relay unit 405. In the mail relay unit 405, the CPU 201 performs an email relay process according to an instruction of the mail relay program. Here, it is assumed that there are two source domain names, “domain A” and “domain B”, corresponding to the application servers 301 and 302. For this reason, a single mail relay unit 405 is provided. However, the number of mail relay units 405 can be plural according to the number of domains of the transmission source.

  The CPU 201 refers to the destination of the header information of the email input to the email relay unit 405 according to the instruction of the email relay program, and only transmits the email according to the mail delivery means specified by the email relay program. Therefore, unlike the mail delivery control unit 403, the mail relay unit 405 does not perform processing such as mail address conversion, temporary storage in a queue, and mail storage in a personal user's mailbox.

  The mail relay unit 405 includes a network interface 409 that is a local host interface that the CPU 201 virtually processes according to an instruction from the OS. The network interface 409 cannot be directly accessed from outside the mail server 306.

  In the mail relay unit 405, the CPU 201 receives an email from the mail delivery control unit 403 through the network interface 409 in accordance with an instruction of the mail relay program. Processing for sending an e-mail from the mail delivery control unit 403 to the network interface 409 will be described in detail later.

  The mail relay unit 405 has a one-to-one correspondence with the network interface 406 that is a network interface dedicated to transmission. Therefore, all e-mails that the CPU 201 transmits to the external mail server in the processing of the mail relay unit 405 are transmitted from the network interface 406.

  In the mail server 306, a domain list database 404 is constructed on the HDD 205. FIG. 4 is a diagram showing a schematic configuration of the domain list database 404.

  The domain list database 404 includes a domain name list 501, a destination IP address list 502 and a port number list 503 corresponding to the domain name list 501. That is, the domain list database 404 is an example of a storage unit that stores information regarding the mail relay unit 405.

  For example, the network interface 409 for the mail relay unit 405 to receive an e-mail is registered in the destination IP address list 502 of the domain list database 404, and the standby port number of the mail relay unit 405 is registered in the port number list 503, respectively. The That is, for the mail relay unit 405, the IP address, the port number, and the corresponding domain names are associated and stored.

  In the processing of the mail delivery control unit 403, the CPU 201 searches the domain list database 404 in accordance with an instruction from the mail server program. At this time, according to the example of FIG. 4, the CPU 201 transmits an e-mail to the mail relay unit 405 via the network interface 409 in the process of the mail delivery control unit 403 according to the instruction of the mail server program.

  Returning to the description of FIG. The mail server 306 has a network interface 408 for the mail processing unit 402 to receive an email from the application server 301 or 302 in accordance with an instruction from the mail server program.

  Although the network interface 408 is provided independently of the network interfaces 406 and 407 in the present embodiment, the network interfaces 406 and 407 may also serve as the network interface 408 in some cases.

  Next, as described above, a description will be given of a procedure of processing for distributing e-mails in the mail server 306 when the domain names of e-mails handled by the mail server 306 are two domains, domain A and domain B. To do.

  FIG. 5 is a flowchart showing processing executed by the CPU 201 in accordance with instructions from the mail server program in the mail delivery control unit 403.

  First, the CPU 201 receives e-mails transmitted from the application servers 301 and 302 in the mail processing unit 402 of the mail server 306 via the network interface 408 (step S601). Next, the CPU 201 analyzes the header information of the electronic mail received in step S601 in the mail delivery control unit 403 of the mail processing unit 402, and extracts the domain name of the sender mail address (From address) (step S602).

  Subsequently, the CPU 201 searches the domain list database 404 and searches whether the domain name of the sender email address extracted in step S602 exists in the domain list database 404 (step S603).

  As a result, if the domain name of the sender mail address extracted in step S602 matches the domain A registered in the domain list database 404 (“YES” in step S603), the process proceeds to step S606.

  In step S606, the CPU 201 searches the domain list database 404 for the destination IP address list 502 and the standby port number list 503 corresponding to the matched domain name A. Then, the CPU 201 connects to the designated port of the network interface 409 acquired by the search in step S606 in the mail processing unit 402 of the mail server 306, and statically transmits an e-mail to the mail relay unit 405 (step S607). Subsequently, the CPU 201 performs processing in the mail relay unit 405 described later in accordance with an instruction of the mail relay program (step S608), and thereafter ends the processing.

  If the domain name of the sender email address extracted in step S602 is not registered in the domain list database 404 (“NO” in step S603), the process proceeds to step S604. In this case, the domain name of the sender email address in the header information of the email received in step S601 is the domain B that does not exist in the domain list database 404.

  In step S604, the CPU 201 analyzes the recipient mail address (mail address specified by To, Cc, Bcc, etc.) of the mail header information as processing of the mail delivery control unit 403. Then, the CPU 201 acquires information on the destination server specified by the MX record or the like of the DNS server or the like according to the instruction of the mail server program.

  As processing of the mail processing unit 402, the CPU 201 connects to the destination server obtained in step S604 via the network interface 407 associated with the mail delivery control unit 403 and transmits an e-mail (step S605). The process is terminated.

  Subsequently, the process of step S608 will be described in detail. FIG. 6 is a flowchart showing the process executed by the CPU 201 in the mail relay unit 405 according to the instruction of the mail server program in step S608 of FIG.

  As processing in the mail relay unit 405 of the mail server 306, the CPU 201 receives the electronic mail transmitted from the mail processing unit 402 in step S607 via the network interface 409 (step S701).

  Subsequently, the CPU 201 analyzes the recipient mail address (mail address specified by To, Cc, Bcc, etc.) of the header information of the electronic mail. Further, the CPU 201 acquires information on the destination server specified by the MX record or the like of the DNS server according to the instruction of the mail relay program (step S702). Then, the CPU 201 connects to the transmission destination server obtained in step S702 via the network interface 406 associated with the mail relay unit 405 and transmits an e-mail (step S703), and then ends the process. .

  According to the above embodiment, when there are two source domain names, domain A and domain B, it is possible to transmit e-mails from different network interfaces 406 and 407 for each domain name.

  As a result, from the mail server that receives the e-mail, it appears that the domain A e-mail is transmitted from the network interface 406 and the domain B e-mail is transmitted from the network interface 407. In this way, the source domain name and the IP address of the source network interface are uniquely determined on a one-to-one basis. Therefore, the problem of false detection of spam mail countermeasures due to a mismatch between the IP address of the mail server that sent the email and the domain name of the sender email address of the sent email is solved.

  Further, when the number of domain names of sender email addresses handled by one mail server is n (n> 2), it can be easily handled by applying the configuration of the above embodiment.

  That is, using one mail server process, n transmission network interfaces (IP addresses) and n-1 mail relay processes, the source domain name and the source network interface IP address are in a one-to-one relationship. Make it correspond. Thus, it appears that the e-mail is sent from an independent mail server for each domain name.

  In the above embodiment, the mail server that is the sender of the electronic mail has a plurality of network interfaces by combining one mail server process and one or more mail relay processes corresponding thereto. Then, the mail server that sent the email automatically sorts the emails so that they are sent from different network interfaces according to the domain name of the sender email address of the email.

  Thereby, since the DNS server can uniquely specify the domain name of the sender mail address of the email and the IP address of the outgoing mail server, it is possible to prevent erroneous detection of an email that is not spam as spam. it can.

  According to the above-described embodiment, the management load does not increase even if the number of source domain names to be handled increases, and the risk of erroneous operation is also reduced, compared to the method of executing the mail server processes as many as the number of source domain names. To do. As a result, in an organization that owns a plurality of domain names, it is possible to consolidate the e-mail system into a small number of mail servers, and it is possible to reduce the cost of constructing the e-mail system and the operational load.

  Although the embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various forms within the scope of the present invention are also included in the present invention.

  That is, some of the above-described embodiments may be combined as appropriate. When a software program that realizes the functions of the above-described embodiments is supplied from a storage medium to a system or apparatus having a computer that can execute the program directly or using wired / wireless communication, and the program is executed Are also included in the present invention.

  Accordingly, the program code itself supplied and installed in the computer in order to realize the functions and processes of the present invention by the computer also realizes the present invention. That is, the computer program itself for realizing the functions and processes of the present invention is also included in the present invention. In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

  Examples of the storage medium for supplying the program include a magnetic storage medium such as a hard disk and a magnetic tape, an optical / magnetomagnetic storage medium, and a nonvolatile semiconductor memory. As a program supply method, a method in which a computer program constituting the present invention is stored in a server on a computer network, and a connected client computer downloads and programs the computer program is also conceivable.

201 CPU
202 BMU
203 ROM
204 RAM
205 HDD
206 Removable Disk Drive 207 Network Interface 208 Communication Line 209 Keyboard Interface 210 Keyboard 211 Pointing Device Interface 212 Pointing Device 213 VRAM
214 Display 215 CPU bus

Claims (4)

There is provided a mail server for transmission that uses n (n is an integer of 2 or more) different domain names as its own domain and transmits an e-mail using each mail address of the n domain names to an external mail server. An email system,
The mail server is
A mail delivery control unit for controlling delivery of the e-mail;
A physical or virtual network interface having at least n different IP addresses, one-to-one corresponding to the n domain names;
A network interface that receives an electronic mail delivered from the mail delivery control unit, and corresponds to at least n-1 network interfaces out of the at least n network interfaces; At least n-1 mail relay units for sending electronic mail to the external mail server via a corresponding network interface;
A storage unit that stores information for identifying the at least n-1 mail relay units in association with a corresponding domain name;
The mail delivery control unit searches the storage unit for information on the mail relay unit corresponding to the domain name of the email to be transmitted to the external mail server, and sends the information to the mail relay unit corresponding to the domain name of the email An e-mail system characterized by transmitting the e-mail. The storage unit stores, as information of the mail relay unit, the IP address, port number, and corresponding domain name of the mail relay unit in association with each of the at least n-1 mail relay units. And
The electronic mail system according to claim 1, wherein the mail delivery control unit transmits the electronic mail according to the IP address and port number. The number of the mail relay units is n-1, and one network interface that does not correspond to the n-1 mail relay units corresponds one-to-one with the mail delivery control unit,
The mail delivery control unit, via the one network interface, when the IP address and port number of the mail relay unit corresponding to the domain name of the email transmitted to the external mail server are not in the storage unit. 3. The electronic mail system according to claim 1, wherein the electronic mail is directly transmitted to the external mail server. Further comprising n terminals or application servers connected to the mail delivery control unit;
The n terminals or application servers have a one-to-one correspondence with the n different domain names, and send an e-mail using the mail address of the corresponding domain name to the mail delivery control unit. ,
The electronic mail system according to any one of claims 1 to 3, wherein the mail delivery control unit controls delivery of electronic mail received from the n terminals or application servers.