Comprehensive analysis of the cause of failure in sending and receiving E-mail

Email is one of the most important applications on the Internet. It provides an extremely convenient and fast communication method. However, many netizens have experienced email sending and receiving failures. Next I will discuss in detail the cause of failure in sending and receiving E-mail to discuss how to improve the success rate of sending and receiving E-mail.

I. general process of sending and receiving E-mail

Generally, E-mail can be sent in two ways: one is through the SMTP sending server provided by the ISP or free email service provider for sending; another method is to create an s mtp sending server on the local machine to directly send emails.

1. Sending and receiving through the mail sending server.

1. In this sending process, the sender first sends an email to the SMTP sending server through a computer. If the email received by the sending server is valid, the mail server uses a "Storage and forwarding" technology to queue the email on the server. When the mail is sent in order, then, the mail server sends the mail to the recipient's receiving server (m x mail exchange server, then, the receiving server forwards the data to the POP3 server (many server systems have the same receiving server and POP3 server ), the recipient finally removes the email from the P OP3 server through the client software on the computer.

2. The process of sending an email directly through the local machine.

Different from the above sending process, some software provides the function of sending an email directly to the receiving server on the local machine. In fact, it is to use the local computer to create an SMTP sending server, the local machine acts as the sending server, bypassing the SMTP sending server provided by I SP or free mailbox. Therefore, this machine acts as both a sender computer and a sender server. Its sending process is similar to the above process, but it reduces the network transmission process between the sender and the sender server and the waiting time of the mail queue.

Ii. Reasons for failed email sending and receiving

As long as there is a problem in the above process, it will cause the failure of sending and receiving E-mail. Therefore, the failure of sending and receiving emails mainly includes the following factors:

1. The account and server attributes of the client software are not correctly configured.

Correctly configuring the mail account of the client software and the server attribute of sending and receiving mails is the key to successfully sending and receiving E-mails. Here, we need to configure two servers, namely the SMTP server and the P OP3 server, as well as the account and password.

SMTP server: the address of the server on which you send emails. Your emails will be sent through this server. For example, xf.hb.cninfo.net. You can also enter the IP address format, for example, 61.136.152.3.

POP3 server: saves emails sent to you. You can use the mail client software, such as Outlook Express, to download these emails to your PC and then process them. If SMTP and POP3 are on the same host, the two are the same, for example, xf.hb.cninfo.net. Similarly, some free mailbox servers generally need to add "p op." In front, such as: pop.163.com.

POP3 and SMTP servers can be entered in the following ways:

1) SMTP. xxxx. xxx pop. xxxx. xxx

2) xxxx. xxx xxxx. xxx

3) SMTP. xxxx. xxx pop3.xxxx. xxx

Account: Actually the account of the POP3 server. You use this account and the corresponding password to receive your email from the POP3 server. For example: Your mailbox is t010405@xf.hb.cninfo. net, then your account is @ the previous "t0000005 ". Some free email accounts need to fill in the full name of the mailbox, not just the front part of @. If you confirm that your password is correct, but cannot pass the password verification, this is generally the reason.

Password: Your account password.

The email can be sent correctly only when the information is correctly filled in. Primary users are most likely to make the above mistakes.

2. the recipient's email address is incorrect.

To ensure that emails can be correctly sent and received by the recipient, it is very important to enter the recipient's email address accurately. The email cannot be sent normally or the recipient cannot receive the email. It is often because the recipient's email address is incorrect. At present, because it is often difficult to register a good account name when you register an email, you have to mix letters, numbers, and some special characters, this often leads to an error when copying the recipient's email address. For example: the lowercase letters "l" and Arabic numerals "1" and lowercase letters "o" are very similar to Arabic numerals "0" and underscores "_" and hyphens "-"., pay special attention when copying the recipient's email address. The recipient's email address is incorrectly entered in two ways:

1) the email address account is incorrect. That is, the part before the recipient's email address @ is incorrect. Here there are two situations, the first case is that the address account is mistakenly filled into other existing mailbox address, such as: Mail xiangkai68@sina.com want to send mail to zxk 71@21cn.com, the address is mistakenly entered as a zxk717@21cn.com (the mailbox address exists), the mail is not sent to the expected mailbox, of course, the recipient can not receive the mail. Another case is that the address account is filled in with other non-existent mailbox addresses, such as: the recipient address is: z xk712871@21cn.com (the mailbox address does not exist), then in the mail server mode sending process, generally, an error message is not displayed, but a message indicating that the email is successfully sent (generally, an email is sent between mailboxes with the same domain name. The Mail Server determines whether the email address is correct and provides an error message ). As long as the email can be correctly sent to the sending server, the mail client software such as O utlook Express and Foxmail will prompt the successful sending. In the next few minutes, you will find that the email you sent will be returned in your mailbox, and inform you that the recipient's email address is invalid or does not exist. Therefore, if you do not check your inbox in time, do you still think the recipient has received an email? In another case, if there is no corresponding email address on the receiving server, some receiving servers will make smart judgments and send them to the correct email address, for example: an email sent to j ohn@myorg.com is sent to the johm@myorg.com, but is typically notified to the sender of the message. When the client software that directly sends an email on the local machine sends an email, because it uses a method directly related to the receiving server, during the sending process, generally, the recipient's email address does not exist. However, if the m x mail exchange server is not the same as the POP3 server, the mail is successfully sent if the mail is sent to the MX mail exchange server, but soon you will receive a Bounce Message.

2) The host address domain name is incorrect: the part after the recipient's email address @ is incorrect. In this case, the email cannot be sent because the host (server) cannot be found after domain name resolution.

Therefore, when entering the recipient's email address, you should be very careful. For friends who often contact you, you can add them to the address book and choose directly when sending the mail. It is best to reply to an email to avoid incorrect copy of the email address. For an uncertain email address, it is best to use the email address verification software to verify the email address before sending it.

3. The mail server is faulty.

For the mail server, failure is inevitable. The email sending server may be temporarily unavailable due to busy network or hacker intrusion. In this case, the email sending server cannot be sent successfully, we only need to wait until the sending server returns to normal before sending again. The upgrading of the mail server system can also lead to changes in the I P address of the mail server, so that the original mail server cannot be accessed (some Users fill in the IP address form when entering the mail server of the client software ). If you have multiple email accounts, you can send them to another sending server. The best way of course is to use software that can provide the local Direct email sending (for example, A dvanced Direct Remailer2.17, hereinafter referred to as ADR,: http://www.mailutilities.com/adr/adr.zip) to send, in this way, you can directly send an email to the receiving server without bypassing the sending server. In addition, it is best to enter the mail server as a domain name instead of an I P address, because this avoids the change of the IP address of the Mail Server caused by the upgrade of the mail system, therefore, the email cannot be sent normally.

4. the email receiving server is faulty.

Similarly, not only are the sending server prone to faults, but the receiving server and POP3 server will also suffer faults. Generally, when the receiving server encounters a temporary fault, emails will not be lost in some cases, because when the receiving server fails, the sending server cannot send emails to the specified receiving server, the sending server resends the email at a specified time interval. For example, the email is sent again after 3 or 0 minutes. If the email cannot be sent successfully, the email is sent again after 60 minutes, and so on, until the message is sent successfully. Generally, when the email receiving server fails, the system administrator will restore the other services to normal in a short period of time. If the email cannot be sent within the specified time period, for example, within 4 or 8 hours, the email will be returned to the sender and the reason for the failure. In fact, during this period, you cannot immediately know that there is a problem with the email receiving server. Therefore, if you use the software that directly sends emails to important emails from the local machine, you can check whether the email receiving server is normal during the sending process, so that you can use other communication methods, for example, you can contact your friend by fax.

There is a problem with the email receiving server, which cannot be solved by the sender. We only have to pray that the email receiving server will recover as soon as possible.

5. domain name resolution server faults.

Generally, when sending an email using an email server, you need to resolve the domain name address of the email sending server, and resolve the domain name address of the email receiving server. Therefore, when the domain name resolution server fails, because the server's domain name address cannot be properly resolved, the user cannot connect to the sending or receiving server, and naturally cannot send and receive emails normally. If you fill in the server address for sending and receiving emails as an I P address, you can avoid failure of the domain name resolution server to send and receive emails normally. If the domain name resolution server fails or the suffix of the email address conflicts with the resolution range of the Domain Name Server, the domain name address of the recipient's email receiving server cannot be resolved. At this time, we only need to replace another domain name resolution server. Therefore, in the network TCP/IP Settings of W indows, you must correctly enter the master DNS and secondary DNS. In this way, when a domain name resolution server encounters a problem, you can call another secondary DNS.

Another point is that China Telecom 169 is illegal internationally, if the Domain Name of the 169 network is resolved by the 163 domain name resolution server on the international network, the domain name cannot be resolved or the resolution is incorrect, resulting in sending failure or sending it to an incorrect mailbox.