IMAP is short for Internet Message Access Protocol. IMAP is a mail retrieval protocol that was developed as a more sophisticated alternative to POP3 . POP3 Stands for post office protocol and was used earlier.

SMTP (Simple Mail Transfer Protocol) - sends mail only

POP (Post Office Protocol) - retrieves mail and manages mailboxes

IMAP (Internet Message Access Protocol) - retrieves mail and manages mailboxes

Two protocols are used to pick up mail in Fedora mail server:

1. POP - Post Office Protocol

2. IMAP - Internet Message Access Protocol

E-mail account type is consist of two protocols. First, the POP3 Post Office Protocol 3 or POP3 and the IMAP With an Internet Message Access Protocol or IMAP.

Along with POP3, IMAP is one of two prevailing electronic mail protocols. IMAP is an acronym for Internet Message Access Protocol. It is is an Application Layer Internet protocol, meaning that it allows an e-mail client application to access electronic mail on a remote mail server.

IMAP differs from the other prevailing e-mail protocol, POP3, in that the client's e-mail is retained in a set of private message directories on the IMAP mail server itself. This allows messages to be easily synchronized across multiple e-mail clients on multiple devices. POP3 protocol delivers messages to the client application for storage on the client device. Messages are subsequently deleted from the POP3 server, making synchronization of multiple devices more difficult.

POP3 was the preferred e-mail protocol when server power and storage capacity were at a premium, and before the rise of ubiquitous Internet-enabled mobile devices. More recently, IMAP has supplanted POP3 as the most predominant e-mail protocol.

All web-mail services (GMail, Yahoo Mail, Hotmail, etc.) are based on IMAP. Microsoft Exchange is also a form of IMAP. Today, nearly all Internet and private electronic mail servers support IMAP.