CentOS Linux mail system setup

Background

Operating system version (Cat/etc/issue): CentOS release 6.5 (Final)

Host Name: mail.gogo.so

Domain Name: gogo.so

Use the Software:

Postfix

Related agreements:

SMTP : Simple Mail Transport Protocol, which is the standard protocol for transmitting mail (TCP port 25). Postfix does not handle any POP and IMAP communication content.

IMAP and POP3 are protocols for receiving messages that describe how to remove them from a mailbox. POP3 and IMAP do not have the ability to post letters at all, only to help the user process the messages received beforehand. Not all users are required to access the mailbox through Pop3/imap. Users with Linux system accounts may set their MUA to read the mail files directly on the same machine.

The composition of the mail system:

A messaging system typically includes: MUA, MTA, MRA, MDA, and so on.

MUA: Mail user agent (mail users agent), common MUA have mutt,outlook express,foxmail, etc., MUA is not directly e-mail sent to the hands of the receiving person, but by the MTA on behalf of the delivery. When you ask MUA to send a message, it simply gives the message to a server running the MTA software (for example, Postfix).

MTA: Mail Transfer agent (message transfer agent), Postfix is an MTA. The MTA's task is to: (1) accept the MUA delegate, deliver the e-mail from one system to another, and (2) receive messages sent from another MTA.

Whenever the MTA receives a MUA letter request, it will first determine whether it should be entertained. Typically, the MTA accepts a letter request if the message is a user from the local system, or a system on the local network, or if any license can forward (relay) the message to another destination's network. On the other hand, the MTA will also decide whether to accept the message, depending on the recipient. If the recipient is a user of the local system, or if the recipient is in another system that it knows how to forward (forward), the MTA will accept the message.

After the MTA has received the message, there are two possibilities: (1) deliver the message to the user on the system, and (2) deliver the message to another MTA to continue the delivery.

MDA: Message Delivery agent (mail delivery proxy). On the MTA at the terminal of the message, after discovering that the recipient is a user on the local system, the message must be sent to the MDA for storage.

MRA: After the mail is placed in the mailbox, it stays there and waits for the recipient to take it away. Recipients use MUA to receive letters and read letters.

CentOS Linux mail system setup