Difference between POP and IMAP protocol

Key Difference: POP and IMAP are both most commonly used Internet standard protocols for reading emails. IMAP is more superior than POP in terms of strength and Flexibility. However, it consumes more resources than POP. Unlike POP, IMAP is not suited to offline use.

POP (Post Office Protocol) is an Internet Protocol standard for reading emails. It was developed in 1984 as a simple way to read or retrieve emails form the mailboxes on SMTP servers. It was designed to be used locally. It has been modified by introducing various versions. In 1985, POP 2 was introduced as the extension of POP 1. It included a rich set of command and replies. In 1988, version 3 of the POP got introduced. It has been devised to serve offline clients to access and retrieve e-mails. POP 3 provides facilities associated with user authentication and mailbox manipulation. POP 3 can be considered as the standard version of POP. It is a command line based protocol which means that all the operations are done by building text commands and then sending them to the server. It is defined by RFC-1939.

The POP3 server listens of port 110. This protocol is popular with the Internet Service Providers as it is simple and cheap to implement. All email messages are downloaded from the server to the local computer. One can also select the option of leaving copies of the emails on the server. Once the messages are downloaded, intercept connection is not required to read the mails.

IMAP stands for Internet Message Access Protocol. IMAP was originally developed in 1986 at Stanford University. IMAP and POP are similar in many ways. However, IMAP offers more features than POP. An email client can also use IMAP to download emails from the server. Generally, it makes use of port 143. The downside of IMAP is that it requires more resources (more disk space on server and more CPU resources). It provides the facility for selective message downloading and deleting, downloading of headers, multiple mailboxes and more. It is defined by RFC-3501.

It is a client/server protocol. The emails that are received are kept by the Internet server. It can work on even a slow connection like modem. The email that one wants to read gets downloaded from the server. Both POP and IMAP protocols are placed between Mail Access Agent and Mail User Agent.

Comparison between POP and IMAP Protocol:

	POP Protocol	IMAP Protocol
Definition	POP (Post Office Protocol) is an Internet Protocol standard for reading emails. It was developed in 1984 as a simple way to read or retrieve emails form the mailboxes on SMTP servers. It was designed to be used locally.	IMAP stands for Internet Message Access Protocol. IMAP was originally developed in 1986 at Stanford University. It is a client/server protocol. The emails that are received are kept by the Internet server. It can work on even a slow connection like modem.
Full Form	Post Office Protocol	Internet Message Access Protocol.
Default settings	It downloads all the messages from the e-mail server onto the user’s computer.	It provides the facility to the user to keep all messages on the server.
Actions performed on the messages	Performed on one’s computer.	Performed directly on the server.
Access to the emails	After the e-mails are downloaded, it can be accessed only using the same computer.	From any computer connected to the Internet.