IMAP4:-

          Internet Message Access Protocol (IMAP) is a protocol for accessing email or bulletin board messages from a mail server or service. IMAP allows a client e-mail program to access remote message stores as if they were local. Email stored on an IMAP server can be manipulated from a workstation at the office, a desktop computer at home or a notebook computer while traveling, without requiring the transfer of messages or files back and forth between these computers.