What is the difference between imap and pop3?

Difference: The POP3 protocol allows the email client to download emails on the server, but operations on the client will not be fed back to the server. IMAP provides two-way communication between webmail and email clients. Operations on the client will be fed back to the server. For operations on the email, the email on the server will also take corresponding actions.

POP3 introduction

POP3, the full name is "PostOfficeProtocol-Version3 ”, namely “Post Office Protocol Version 3”. It is a member of the TCP/IP protocol suite and is defined by RFC1939. This protocol is primarily intended to support remote management of email on the server using a client. The POP3 protocol that provides SSL encryption is called POP3S.

POP protocol supports "offline" email processing. The specific process is: the email is sent to the server, the email client calls the email client program to connect to the server, and downloads all unread emails. This offline access mode is a store and forward service that sends emails from the email server to a personal terminal machine, usually a PC or MAC. Once the email is sent to the PC or MAC, the email on the mail server will be deleted. However, most of the current POP3 mail servers can "only download mails and not delete them on the server side", which is an improved POP3 protocol.

POP3 protocol features:

POP3 protocol default port: 110

POP3 protocol default transmission protocol: TCP

POP3 protocol applicable Architecture structure: C/S

Access mode of POP3 protocol: Offline access

POP3 protocol is shown in the figure below.

POP3 Scope of application:

POP is an email protocol suitable for the offline model of C/S structure, which has been developed The third version is called POP3. The offline model cannot be operated online, and POP does not support extended operations on server emails. This process requires the more advanced IMAP4 protocol to complete. Supports POP protocol to use ASCII code to transmit data messages. These data messages can be instructions or responses.

imap introduction

IMAP (InternetMailAccessProtocol, Internet Mail Access Protocol) was formerly called Interactive Mail Access Protocol (InteractMailAccessProtocol). IMAP is an email retrieval protocol developed by Stanford University in 1986. Its main function is that mail clients (such as MSOutlookExpress) can obtain mail information from the mail server, download mails, etc. through this protocol. The current authoritative definition is RFC3501. The IMAP protocol runs on top of the TCP/IP protocol and uses port 143. The main difference between it and the POP3 protocol is that users do not need to download all emails, but can directly operate the emails on the server through the client.

imap features:

Similar to the POP3 protocol, IMAP (Internet Message Access Protocol) also provides user-oriented email collection services. The commonly used version is IMAP4.

IMAP4 improves the shortcomings of POP3. Users can decide whether to collect, delete and retrieve specific parts of the email by browsing the letter headers, and can also create or change folders or mailboxes on the server. In addition to supporting the offline operation mode of the POP3 protocol, it also supports online operation and disconnection operation. It provides users with the function of selectively receiving mail from the mail server, server-based information processing function and shared mailbox function. The offline mode of IMAP4 is different from POP3 in that it will not automatically delete emails that have been taken out on the mail server. Its online mode and disconnection mode also access the mail server as a "remote file server", which is more flexible and convenient. IMAP4 supports multiple mailboxes.

These features of IMAP4 are very suitable for users who operate mail between different computers or terminals (for example, you can operate the same mailbox on a mobile phone, PAD, or mail agent program on a PC), as well as those who use multiple mailboxes at the same time. mailbox user.

Function of IMAP:

Compared with POP3, the "summary browsing" method of email provided by IMAP greatly improves the efficiency of email. Browsing speed can effectively save customers valuable time. This feature is very useful for users who often receive a large number of emails and want to prevent spam. After users create an IMAP account, they can specify which folders are displayed and which folders are hidden. The summary browsing function provided by IMAP allows users to make a decision after reading the arrival time, sender, subject, size and other information of all emails. You can also enjoy the decision of selectively downloading attachments. For example, if the user receives a letter with 3 attachments, the user can only download 1 of them according to his or her own needs, thus saving a lot of valuable time. This avoids the passive situation of having to receive all the emails locally before making a judgment when using the POP3 method to receive mails.

The difference between pop3 and imap

POP3 protocol allows email clients to download emails on the server, but operations on the client (such as moving emails, marking them as read, etc.) will not be fed back to the server.

IMAP provides two-way communication between webmail and email clients. The operations on the client will be fed back to the server. The operations on the email will also take corresponding actions on the email on the server.

Compare through the following table to see the difference between using IMAP and POP on the client:

At the same time, IMAP provides convenience like POP Email download service allows users to read offline. The summary browsing function provided by IMAP allows you to make a decision whether to download after reading all the email arrival time, subject, sender, size and other information. In addition, IMAP better supports accessing new emails at any time from multiple different devices.

In short, IMAP overall brings a more convenient and reliable experience to users. POP is more prone to losing emails or downloading the same emails multiple times, but IMAP avoids these problems well through the two-way synchronization function between the mail client and webmail.

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