IMAP (Internet Message Access Protocol) is richer in functionality than POP and is designed to allow clients to access and manage mailboxes on the server as if they were local. IMAP is a much more complex protocol than POP, with less client support. IMAP4 is the latest implementation of IMAP. Although the messages reside on the mail server clients that support IMAP can manipulate these messages in many ways.


POP3, which is an abbreviation for Post Office Protocol 3, is the third version of a widespread method of receiving email. Much like the physical version of a post office clerk, POP3 receives and holds email for an individual until they pick it up. And, much as the post office does not make copies of the mail it receives, in previous versions of POP3, when an individual downloaded email from the server into their email program, there were no more copies of the email on the server; POP automatically deleted them.