JP2003169095A - E-mail system and e-mail distribution method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a person who is suffered with junk mail to prevent junk mail without taking any countermeasures. <P>SOLUTION: When one user performs a process of sending electronic mail, the electronic mail is inputted to a transmit mail server device 12 from a transmit mail input part 11. A transmit mail reception part 14 of this transmit mail server device 12 stores electronic mail sent within a certain time. A decision part 15 of the transmit mail server device 12 decides whether there is electronic mail from the same user to a plurality of mail addresses of the same domain name within the time and the number of the distribution destination mail addresses is larger than a specified number, and deletes the mail without distributing it when the number of the mail addresses is larger than the specified number, but distributes the mail when less than the specified number. <P>COPYRIGHT: (C)2003,JPO

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 provided with a mail server device for sending and receiving electronic mail and an electronic mail delivery method.

[0002]

2. Description of the Related Art In recent years, it has become common to exchange e-mail using a mobile phone. The e-mail address of a mobile phone is often different only in an account for a specific domain name, and the number of addresses in that specific domain name is enormous considering the prevalence of mobile phones. The email address is
It is marked with "user name @ domain name" such as "name@matushishita.co.jp". The domain name is an IP address that is a list of numerical values replaced by a character string so that it can be easily understood by humans.

Since names and telephone numbers are mainly used for mail address accounts, there is a great possibility that someone who does not know the address can find the address simply by inputting unspecified characters. There are many people who are annoyed by the flood of advertisements and mischief emails called (spam). As measures against this, there are techniques such as changing the mail address and the technique disclosed in Japanese Patent Laid-Open No. 2000-339236.

The technical contents disclosed in Japanese Patent Laid-Open No. 2000-339236 will be described below. FIG. 9 is a block diagram showing the configuration of the mischievous mail prevention device disclosed in the publication. In this figure, the server device 1 for electronic mail delivery sends all mail addresses corresponding to a certain format to a specific person. For example, the email address is ueda @ xxxxxx. server. com or ueda. xxxxxx @ server. com
For emails in the format like this, transfer to the email address registered for the email corresponding to any "xxxxxx" in the email address, or deliver to the specific mailbox registered for the email I do.

By allowing characters of arbitrary length in the "xxxxxx" part, theoretically unlimited mail addresses are possible, and even if a sufficiently long fixed-length character string is allowed, it is extremely difficult. You can deliver from many email addresses to one mailbox. This makes it easy for the user to reject or delete a mail to a mail address that does not include "xxxxxx" that he / she decides to receive. In normal use, the mail user will notify each person who may send a mail with a different mail address, and discard or ignore the mail that reaches the mail address other than all the notified mail addresses. .

It is assumed that the user has previously registered the address of the mail to be received in the server device 1 and has acquired the mail address for himself / herself as the destination of the received mail. If you use this email address as "name @ ser
“Ver”. The server device 1 performs any of the following to prepare an unlimited number of mail addresses. (1) Characters that are not used in the name part (for example, "." Are used to treat all mails addressed to "name. Arbitrary character string @server" as mails addressed to "name @ server", and redistributed as necessary or Put it in your mailbox.

(2) Domain Name Servi
using the MX (Media eXchange) field of “ce”
me @ any domain name. Notify the world that the server 1 will receive the mail addressed to "server", treat all the received mails as mail addressed to "name @ server", and redistribute or put them in the mailbox as necessary.

Further, the server device 1 includes a mail receiving unit 3
In the above, after checking the address or address pattern of the sent mail, according to the instruction given in advance by the user, the mail is discarded, the mail is rejected by sending an error mail, or the user's Performs processing such as adding some fields that can be processed by mail reader software.

The user has any one or more or all of the means for performing the following processing when giving an instruction to the server device 1. (1) Specify a specific email address and processing method,
After that, the mail that reaches the mail address will be processed in that way. (2) Designate a pattern of a certain specific mail address and its processing method, and process the mail that arrives at a mail address address that matches the pattern thereafter by that method. (3) Specify the processing method for all mail addresses, and process all subsequent mails by that method.

For this purpose, a processing content storage unit 2 for storing a designated address and a processing method corresponding to the designated address as a pair is provided inside the server device 1. FIG. 10 is an example of a table stored in the processing content storage unit 2. One row of the table 2a has an option to store a field for storing an address or an address pattern, a field for storing a processing method corresponding to the address or the address pattern, and a parameter of the processing method used in the processing method. It consists of fields to be stored.

The server device 1 collates the address of the received mail with the designated address or address pattern registered in the table 2a, and if there is a matching address or address pattern in the table 2a, it matches. Performs processing corresponding to the address or address pattern. If processing is specified for all email addresses, processing is performed for all emails that reach the user.

The server device 1 also has an input / output unit 4 for a user to register / reference a processing method, and a user requests a list of processing methods via the input / output unit 4. List of all processing methods corresponding to the user name (including address patterns and options)
To the user. When registering the processing method from the user via the input / output unit 4, the old registration is deleted, the registered content is changed, and the new registration is performed.

[0013]

However, the conventional unsolicited email protection system has the following problems. That is, the person who is suffering from the trouble must deal with the unwanted mail (for example, (1) to (3) described above), and the operation is troublesome. Especially, it is easy for a person who is not familiar with the operation. is not.

In addition, a disposable mail address is created, a mail address dedicated to a specific person is created,
Even if you create an e-mail address that only the recipient can know, it is possible to detect the true e-mail address, so it is difficult to completely prevent spam.

The present invention has been made in view of the above point, and an e-mail system and an e-mail delivery system which can prevent undesired mails without taking any action by a person suffering from the junk mails. The purpose is to provide a method.

[0016]

An electronic mail system according to a first aspect of the present invention comprises a mail server device for connecting users, and the mail server device deletes electronic mail having a predetermined number of destinations or more. Adopt a configuration that does.

According to this structure, since the electronic mails to the predetermined number or more are deleted, the spam mail such as SPAM is not delivered, and the person who has been troubled until now does not take any action. Even stop receiving junk mail delivery.

An electronic mail system according to a second aspect of the present invention is the electronic mail system according to the first aspect of the present invention, wherein the mail server device deletes electronic mail having a predetermined number of destinations having a common domain name. Adopt a configuration that does.

According to this structure, since the e-mails having the same number of destinations with the same domain name or more are deleted,
Spam and other unsolicited emails will no longer be delivered, and people who have been annoying until now will not receive unsolicited emails without taking any action.

An electronic mail system according to a third aspect of the present invention is the electronic mail system according to the first or second aspect of the present invention, wherein the mail server device has a mail address of the user of the electronic mail registered in advance. If
Use a configuration that does not delete the email.

According to this structure, a user who has registered his / her own mail address in advance can send an electronic mail to a predetermined number or more of destinations. As a result, even a user who issues an e-mail newsletter can send e-mail as usual by registering his or her e-mail address in advance. The mail address may be registered by the administrator who manages the mail server device, for example, by sending an e-mail or by telephone.

According to a fourth aspect of the present invention, there is provided an electronic mail delivery method, an identification step of identifying electronic mails having a predetermined number or more, a registration step of registering a mail address of a user who uses the electronic mail, and a destination. If the email addresses of email users with a certain number or more are unregistered, delete the email, and if the email addresses of email users with a certain number or more of the registered email addresses are registered, delete the email. And a delivery step of delivering.

According to this method, when the number of destinations is a predetermined number or more,
If the sender user's email address is registered, the email is not deleted. If the sender user's email address is unregistered, the email is deleted. Although the regular mail will be delivered, spam mail such as SPAM will not be delivered, and the person who has been troubled until now will not receive the junk mail without any action.

According to a fifth aspect of the present invention, there is provided an electronic mail delivery method, wherein an identification step for identifying electronic mails having a common domain name and a predetermined number or more, and a mail address of a user who uses the electronic mail are registered. The registration process, the deletion process to delete the email if the email address of the email user who has more than the specified number of destinations is not registered, and the email address of the email user who has the specified number of destinations or more registered If so, a delivery step of delivering the mail is provided.

According to this method, if the number of destinations having a common domain name is more than a predetermined number and the sender user's mail address is already registered, the email is not deleted and the sender user's mail address is If you do not register, e-mail will be deleted, so even if the number of recipients is more than the specified number, legitimate mail will be delivered, but spam mails such as SPAM will not be delivered Those who were not able to receive unsolicited emails without taking any action.

The electronic mail delivery program of the invention according to claim 6 determines the number of destinations for determining whether or not the electronic mail transmitted from the electronic device having the mail communication function has a predetermined number of destinations or more. When the e-mail has a predetermined number of destinations or more, a user authentication step of determining whether or not the e-mail address of the sender user of the e-mail has already been registered, and the e-mail has a predetermined e-mail address. If the number of recipients is more than one and the sender's email address of the email is already registered, or if the email has less than a predetermined number of recipients, the email is sent to all recipients. And a step of delivering the email to the email address of the email, wherein the email has a predetermined number of recipients or more, and If the e-mail address is not registered,
And a mail deleting step of deleting the mail.

By using this program in an existing electronic mail system, it becomes impossible for anyone other than a properly registered user to send an electronic mail with a specified number of destinations or more. Delivery can be prevented. As a result, a person who has been troubled until now does not receive the junk mail even if no action is taken.

The electronic mail delivery program of the invention according to claim 7 determines whether or not the electronic mail transmitted from the electronic device having the mail communication function has a predetermined number of destinations having the same domain name. The step of determining the number of recipients and the step of determining whether or not the email address of the sender user of the email is already registered if the email has a predetermined number of recipients having a common domain name. A user authentication step to make a determination; a case where the email has a predetermined number of destinations having a common domain name, and the email address of the sender user of the email has already been registered; If there are less than a specified number of recipients that share or do not share the domain name, deliver the email to all recipient email addresses A mail delivery step of deleting the mail if the e-mail has a predetermined number or more of recipients and the mail address of the sender user of the mail is unregistered. To do.

By using this program in an existing electronic mail system, it becomes impossible for anyone other than a properly registered user to send an electronic mail with a specified number of destinations or more. Delivery can be prevented. As a result, a person who has been troubled until now does not receive the junk mail even if no action is taken.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The essence of the present invention is to prevent unsolicited emails such as SPAMs from being delivered by deleting emails addressed to a predetermined number or more in a mail server device connecting users. is there.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a main part of an electronic mail system according to Embodiment 1 of the present invention.

In the figure, an electronic mail system 10 of the present embodiment is provided with a transmission mail input unit 11 for receiving an electronic mail transmitted by a mail communication function installed in an electronic device such as a personal computer or a mobile phone. , A transmission mail server device 12 that performs a process of delivering an electronic mail input from the transmission mail input unit 11 to a destination user, and a transmission mail output unit that outputs a transmittable electronic mail output from the transmission mail server device 12 And 13 are provided.

The outgoing mail server device 12 stores the outgoing mail reception unit 14 that stores the electronic mail that has been processed for transmission within a fixed time, and the electronic mail that has been processed for transmission within a fixed time.
The same domain name from the user (for example, "name @ mat
sushita. co. "matsus" in "jp"
hita. co. jp "portion), and whether or not the mail has been sent to a plurality of mail addresses, and the mail has been sent to a plurality of mail addresses. If the number is less than the predetermined number, the e-mail is deleted, and if the number is less than the predetermined number, the e-mail is output as it is without being deleted.

The determination unit 15 of the mail server device 12 is configured to have a CPU (not shown), and this CPU is the recording medium 1
It operates according to the program (e-mail delivery program) recorded in 5A. The recording medium 15A may be a semiconductor memory, a magnetic disk, an optical disk, a magneto-optical disk, or the like.

FIG. 2 is a flowchart showing the operation of the electronic mail system 10 according to this embodiment. First,
E-mails that have been sent and processed are accumulated within a fixed time (step 20). After accumulating emails that have been sent and processed within a certain period of time, 1
It is determined whether or not it is sent from the user to a plurality of mail addresses having the same domain name (step 22). In this judgment, when it is judged that the mail is sent from one user to a plurality of mail addresses of the same domain name, it is judged whether or not the number of addresses is a predetermined number or more (step Two
4). In this determination, if the number of addresses of the same domain name is less than the predetermined number, the mail is delivered as it is (step 26). Step 2 after sending the email
Return to 0.

On the other hand, if the number of addresses of the same domain name is more than the predetermined number, the mail is deleted without being delivered (step 28). Then, after the mail is deleted, the user who sent the electronic mail is notified that the electronic mail has been deleted (step 30). After sending the e-mail deletion notice, the process returns to step 20.

On the other hand, when it is judged in step 22 that the electronic mail processed within the fixed time is not sent from one user to a plurality of mail addresses having the same domain name, that is, one mail address is sent. If it is sent to the destination, the mail is delivered as it is (step 26).

As described above, according to the electronic mail system 10 of the present embodiment, when an electronic mail is delivered to a plurality of mail addresses having the same domain name, the number of delivered mail addresses is a predetermined number or more. If so, delete the email without delivering it. As a result, the person who has been troubled until now does not receive the junk mail delivery without any action. Further, it is possible to receive e-mails for a number of people less than a predetermined number, such as broadcast e-mails between friends, as usual.

(Embodiment 2) FIG. 3 is a block diagram showing a configuration of a main part of an electronic mail system according to Embodiment 2 of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to.

The electronic mail system 30 of this embodiment
Is a transmission mail server device 31 having a storage unit 32 for registering the mail address of the user who sent the e-mail.
Is equipped with. Judgment unit 33 of outgoing mail server device 31
Is an email sent to more than a specified number of email addresses with the same domain name.If the email address of the sender of the email is unregistered, the email is deleted and registered. Do not delete if there is. The registration of the mail address may be performed by the administrator who manages the outgoing mail server device 31, for example, by sending an e-mail or by telephone.

The determination unit 33 of the outgoing mail server device 31 has a CPU (not shown), and this CPU is the recording medium 3.
It operates according to the program (e-mail delivery program) recorded in 3A. The recording medium 33A may be a semiconductor memory, a magnetic disk, an optical disk, a magneto-optical disk, or the like.

FIG. 4 is a flowchart showing the operation of the electronic mail system 30 according to this embodiment. First,
E-mails that have undergone transmission processing are accumulated within a fixed time (step 40). After accumulating emails that have been sent and processed within a certain period of time, 1
It is determined whether or not it is sent from the user to a plurality of mail addresses having the same domain name (step 42). In this judgment, if it is judged that the e-mail processed within the fixed time is sent from one user to multiple mail addresses of the same domain name, is the number of addresses equal to or more than a predetermined number? It is determined whether or not (step 44). If the number of addresses of the same domain name is less than the predetermined number in this determination, the mail is delivered as it is (step 46). Then, after the delivery process of the mail is performed, the process returns to step 40.

On the other hand, if the number of addresses of the same domain name is not less than the predetermined number, it is determined whether or not the mail address of the sender user of the electronic mail is registered (step 48). In this determination, if the mail address of the user who sent the e-mail is registered, the process proceeds to step 46, and the mail is delivered. On the other hand, if the email address of the email sender user is not registered, the email is deleted without being delivered (step 50). After the delivery of the email, the user who sent the email is notified that the email has been deleted (step 52). After sending the e-mail deletion notice, the process returns to step 40.

On the other hand, when it is judged in step 42 that the electronic mail processed within the fixed time is not sent from one user to a plurality of mail addresses having the same domain name, that is, one mail address is sent. If the mail is sent to the user, the mail is delivered as it is (step 46).

As described above, the electronic mail system 30 of the present embodiment sends an electronic mail to a user who has registered his / her own mail address in advance to a predetermined number or more of mail addresses of the same domain name. Allow As a result, even a user who issues an e-mail newsletter or the like can send e-mails as before by registering his or her e-mail address in advance.

(Third Embodiment) FIG. 5 is a block diagram showing a configuration of a main part of an electronic mail system according to a third embodiment of the present invention.

In this figure, the electronic mail system 50 of the present embodiment receives a received mail input section 51 for receiving an electronic mail transmitted from a transmission mail server device (not shown), and inputs from the received mail input section 51. A received mail server device 52 that receives the received electronic mail and delivers the electronic mail that is output by the mail communication function of an electronic device such as a personal computer or a mobile phone, and a received mail that outputs the electronic mail output from the received mail server device 52. Output unit 53
And is configured.

The received mail server device 52 stores received e-mails that have been processed for reception within a fixed time, and receives e-mails processed within a fixed time from one user to a plurality of mail addresses. If it is sent to multiple e-mail addresses by judging whether it is sent or not, and if the number of e-mail addresses is equal to or more than a prescribed number, the e-mail is deleted and less than the prescribed number. In that case, the determination unit 55 that outputs the mail as it is without deleting the mail is configured.

The determination unit 55 of the received mail server device 52 has a CPU (not shown), and this CPU is the recording medium 5.
It operates according to the program (e-mail delivery program) recorded in 5A. The recording medium 55A may be a semiconductor memory, a magnetic disk, an optical disk, a magneto-optical disk, or the like.

FIG. 6 is a flowchart showing the spam mail prevention operation of the electronic mail system 50 according to this embodiment. First, the received electronic mail is accumulated within a fixed time (step 60). After accumulating the received e-mails within a fixed time, it is determined whether or not the received e-mails within that time are sent from one user to a plurality of mail addresses ( Step 62). In this judgment, if the electronic mail is sent from one user to a plurality of mail addresses, it is judged whether or not the number of the mail addresses is a predetermined number or more (step 64).

In this determination, if the number of mail addresses is equal to or larger than the predetermined number, the mail is deleted without being received (step 66). After deleting the mail, the user who sent the e-mail is notified of the deletion (step 68). On the other hand, if the number of mail addresses is less than the predetermined number, the mail is received without being deleted (step 70). On the other hand, in step 62, the electronic mail processed within the fixed time is not sent from one user to a plurality of mail addresses (that is, it is sent to one mail address). In the case), the mail is received as it is (step 70).

As described above, according to the electronic mail system 50 of this embodiment, when an electronic mail is sent from one user to a predetermined number or more of mail addresses, the mail is deleted, If the number is less than the predetermined number, it is received as it is without being deleted. As a result, a person who has been troubled until now does not receive the junk mail without taking any action. Further, it is possible to receive e-mails for a number of people less than a predetermined number, such as broadcast e-mails between friends, as usual.

(Fourth Embodiment) FIG. 7 is a block diagram showing the configuration of the main part of an electronic mail system according to a fourth embodiment of the present invention. In addition, in FIG.
The same reference numerals are given to the portions common to.

In this figure, an electronic mail system 70 according to the present embodiment comprises a received mail server device 71 having a storage unit 72 for registering the mail address of an electronic mail sender user. The determination unit 73 of the received mail server device 71 is a case where the same sender has sent e-mail addressed to a predetermined number or more of e-mail addresses, and the e-mail sender user's e-mail address is not registered. In that case, the mail is deleted without receiving it, and if it is already registered, it is received without being deleted. The registration of the mail address may be performed by, for example, issuing an e-mail to the administrator who manages the receiving mail server device, or by making a telephone contact to set the administrator.

The determination unit 73 of the received mail server device 71 has a CPU (not shown), and this CPU is the recording medium 7.
It operates according to the program (e-mail delivery program) recorded in 3A. The recording medium 73A may be a semiconductor memory, a magnetic disk, an optical disk, a magneto-optical disk, or the like.

FIG. 8 is a flowchart showing the operation of the electronic mail system 70 according to this embodiment. First,
The received e-mails are accumulated within a fixed time (step 80). After accumulating received emails within a certain time, the number of emails processed within that time is 1
It is determined whether the user has addressed to a plurality of mail addresses (step 82). In this judgment, if the mail is sent to a plurality of mail addresses, it is judged whether or not the number of mail addresses is a predetermined number or more (step 84).

In this determination, if the number of addresses is equal to or more than the predetermined number, it is determined whether or not the mail address of the electronic mail transmission source user is registered (step 8).
6) If it is not registered, the mail is deleted without receiving it (step 88). Then, the user who sent the email is notified that the email has been deleted (step 9).
0). On the other hand, if the email address of the user who sent the email is already registered, the email is directly received without being deleted (step 92). On the other hand, in step 82, if the electronic mail processed within the fixed time is not sent from one user to a plurality of mail addresses, that is, if it is sent to one mail address. , Receives the mail as it is (step 92).

As described above, according to the electronic mail system 70 of the present embodiment, when the same sender simultaneously sends electronic mail to a predetermined number or more of mail addresses, the sender of the electronic mail If the user's email address is registered, the email is received without being deleted, and if the email address is not registered, the email is deleted without receiving the email. As a result, even a user who issues an e-mail newsletter can send e-mail as before by registering his or her e-mail address in advance.

[0060]

As described above, according to the present invention,
Since the mail server device deletes what is considered to be junk mail before delivery, the mail recipient does not need to take measures against the junk mail. Also, users who send multiple e-mails can use it as before if they register in advance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an electronic mail system according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the electronic mail system according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a main part of an electronic mail system according to a second embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the electronic mail system according to the second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a main part of an electronic mail system according to a third embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of the electronic mail system according to the third embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a main part of an electronic mail system according to a fourth embodiment of the present invention.

FIG. 8 is a flowchart for explaining the operation of the electronic mail system according to the fourth embodiment of the present invention.

FIG. 9 is a block diagram showing the configuration of a conventional mischievous email protection device.

FIG. 10 is a diagram showing a table stored in a processing content storage unit of a conventional mischievous mail prevention device.

[Explanation of symbols]

10, 30, 50, 70 E-mail system 11 Sent mail input section 12, 31 Outgoing mail server device 13 Outgoing mail output section 14 Sending mail reception section 15, 33, 55, 73 Judgment unit 15A, 33A, 55A, 73A recording medium 32, 72 storage 51 Received mail input section 52,71 Incoming mail server device 53 Received mail output section 54 Received mail reception section

Claims (7)

[Claims] 1. An electronic mail system comprising a mail server device for connecting users, wherein the mail server device deletes electronic mail having a predetermined number or more of destinations. 2. The electronic mail system according to claim 1, wherein the mail server device deletes electronic mail having a predetermined number of destinations having a common domain name. 3. The mail server device, if the mail address of the user of the electronic mail is registered in advance,
The said mail is not deleted, The claim 1 characterized by the above-mentioned.
Alternatively, the electronic mail system according to claim 2. 4. An identification step of identifying an electronic mail having a predetermined number or more of destinations, a registration step of registering a mail address of a user who uses the electronic mail, and a mail of an electronic mail user having a predetermined number or more of destinations. A deletion step of deleting the mail if the address is unregistered, and a distribution step of distributing the mail if the mail address of the user of the e-mail having a predetermined number of destinations or more is registered. A characteristic e-mail delivery method. 5. An identification step of identifying an electronic mail having a predetermined number of destinations having a common domain name, a registration step of registering a mail address of a user who uses the electronic mail, and a predetermined number of destinations or more. A deletion step of deleting the email if the email address of the email user is not registered, and a delivery step of delivering the email if the email address of the email user with a predetermined number or more of destinations is registered. An electronic mail delivery method comprising: 6. A destination number determining step of determining whether or not an electronic mail transmitted from an electronic device having a mail communication function has a predetermined number or more of destinations, and the electronic mail has a predetermined number or more of destinations. A user authentication step of determining whether or not the email address of the sender user of the email has been registered, and the email has a predetermined number of destinations or more, When the email address of the sender user of the email is already registered, and when the email has less than a predetermined number of recipients, the email delivery step of delivering the email to all recipient email addresses, If the e-mail has more than a predetermined number of destinations and the e-mail address of the sender user of the e-mail is not registered, the e-mail is An e-mail delivery program comprising: an e-mail deleting step of deleting. 7. A destination number determination step of determining whether or not an electronic mail transmitted from an electronic device having a mail communication function has a predetermined number of destinations having a common domain name, the electronic mail If there is a predetermined number or more of recipients having a common domain name, a user authentication step of determining whether or not the email address of the sender user of the email is already registered, and the email is There are more than a predetermined number of destinations with a common domain name, and the email address of the sender of the email is already registered, and the email has a common or non-common domain name. A mail delivery step of delivering the mail to all destination email addresses when the email has less than the number of recipients, and the email is predetermined. An electronic mail delivery program comprising: a mail deletion step of deleting the mail if the mail address of the sender user of the mail is unregistered, which has more than one destination.