Internet Message Access Protocol (IMAP) is an application layer internet protocol. It is used by email clients to retrieve email message from a mail server over a TCP/IP connection. IMAP allows you to access electronic mail or message that are kept on a mail server. IMAP supports multiple logins, it allows the end user to simultaneously connected to the email server with the different device.
IMAP allows an email client to access email on a remote mail server.IMAP offers us to access message from Multiple computers and it is support for concurrent access to shared mailboxes. Advantages over POP as follows: Connected and disconnected modes of operation, Multiple clients simultaneously connected to the same mailbox, Access to MIME message parts and partial fetch.
An IMAP server typically listens on the port number 143. IMAP over SSL (IMAPS) is assigned the port number as 993.