Three commonly used e-mail protocols

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Our commonly used e-mail protocols are SMTP,POP3,IMAP4, which are subordinate to the TCP/IP protocol family, and are established by default by TCP ports 25, 110, and 143 respectively.

SMTP ( Simple Mail Transfer Protocol) is simply a message transfer protocol, which is a set of rules for sending mail from the source address to the destination, and it controls the way the letters are relayed. The SMTP protocol is a TCP/IP protocol cluster that helps each computer find its next destination when sending or relaying letters.
SMTP authentication, in short, requires that the account name and password must be provided before the SMTP server can be logged in, which makes it possible for spammers to have no opportunity. The purpose of increasing SMTP authentication is to protect users from spam.
SMTP[2] has been the de facto standard for e-mail transmission.

            IMAP ( Internet Mail Access Protocol,internet Mail Access Protocol) was formerly known as the Interactive Mail Access Protocol (Interactive mail, Access Protocol). IMAP was an email acquisition protocol developed by Stanford University in 1986. Its main role is that the mail client (for example, Ms Outlook Express) can obtain mail information from the mail server via this protocol, download messages, and so on. The
is a new protocol that is better than pop. He's not the only one who wants pop. Download the message, delete the message from the server, or ask if there is a new message, or you can decide how the client requests the mail server to submit the received message, requesting that the mail server download only the selected message instead of all the messages. The client can read the title of the message and the sender's name before deciding whether to download the message. Through the user's client e-mail program, IMAP allows users to create and manage mail folders or mailboxes on the server, delete messages, query part or all of a letter, and do all of this without having to download the message from the server to the user's personal computer
Common mail clients that support the type of IMAP are: Thundermail,foxmail,microsoft Outlook, and so on.

           POP3, full name "Post Office Protocol-version 3", or "Post Office Protocol version 3" This agreement is primarily intended to support the use of clients to remotely administer e-Mail on the server. The Pop Post Office Protocol is responsible for retrieving e-mail from the mail server. It requires the mail server to do one of the following tasks: Retrieving the message from the mail server and deleting it from the server, retrieving the message from the mail server without deleting it, and not retrieving the message, just asking if a new message arrives. The
Pop applies to the E-mail protocol of the offline model of the C/s structure. The offline model cannot be operated online, and pop does not support extended operations on server mail, which requires a more advanced IMAP4 protocol to complete.
POP3 Protocol Default port: POP3 protocol Default transport protocol: TCP
POP3 protocol for the architecture: C/S
POP3 protocol access mode: offline Access
--------------------------- ------------the difference between POP3 and IMAP--------------------------------------

The POP3 protocol allows e-mail clients to download messages on the server, but actions on the client, such as moving messages, marking read, and so on, are not fed back to the server. For example, the client collects 2 messages from the mailbox and moves them to other folders, and the messages on the mailbox server are not moved at the same time.
While IMAP provides two-way communication between the webmail and the email client, the client's actions are fed back to the server, the messages are manipulated, and the messages on the server do the corresponding actions.

IMAP also provides a better way to access messages from multiple devices. If you're in your organization, on your phone, and then you're checking your email at home, IMAP ensures that you'll be able to access new messages from any device at any time.

IMAP, like POP3, provides a convenient e-mail download service that allows users to read offline. The summary browsing feature provided by IMAP allows you to decide whether or not to download after you have read all the message arrival time, subject, sender, size, and so on.

Finally, IMAP can provide a more stable usage experience on the whole. POP3 is easier to lose messages or to download the same messages more than once, while IMAP avoids this by using bidirectional synchronization between the mail client and the network mailbox.

Three commonly used e-mail protocols