SMTP, POP3 and IMAP mail protocols

Table of contents

​ ​SMTP

​ ​POP

​ ​IMAP

​ ​Summary

​ ​MX records in DNS records

Today, on the first day of joining the company, the company asked me to configure personal intranet and extranet mailboxes, which made me dizzy. I didn’t know much about mailboxes before, and I don’t usually use mailboxes. At most, there is a QQ Just an email. Today, taking advantage of the configuration of the company’s personal intranet and intranet mailbox, I checked the information and sorted out the differences between these three protocols.

First, SMTP, POP, and IMAP are all mail-related protocols. SMTP is mainly responsible for sending mail, while POP and IMAP are responsible for receiving mail.

SMTP

SMTP (Simple Mail Transfer Protocol), the Simple Mail Transfer Protocol, the default port is 25 , and the default port after SSL protocol encryption is 465 . As the name implies, it is actually a very simple transmission protocol, no authentication is required, and the sender’s email address can be arbitrarily declared by the sender. Using this feature, any sender can be faked. It is a protocol for transferring mail from a source address to a destination address, and it is used to control the way mail is relayed. The SMTP protocol belongs to the TCP/IP protocol suite, which helps each computer find the next destination when sending or relaying letters. SMTP is a “push” protocol that does not allow messages to be “pulled” from remote servers on demand.

SMTP authentication : Simply put, it is required to log in to SMTP only after providing an account name and password