What is IMAP (Internet Message Access Protocol)?

Internet Message Access Protocol (IMAP) is an Internet standard protocol utilized by email customers to recover email messages from a mail server over a TCP/IP association. An IMAP server commonly listens on port number 143. IMAP over SSL/TLS (IMAPS) is alloted the port number 993. IMAP was planned by Mark Crispin in 1986. To cryptographically secure IMAP associations, IMAPS on TCP port 993 can be utilized, which uses SSL/TLS.