Page "Post Office Protocol" Paragraph 1

POP supports simple download-and-delete requirements for access to remote mailboxes ( termed maildrop in the POP RFC's ).

Although most POP clients have an option to leave mail on server after download, e-mail clients using POP generally connect, retrieve all messages, store them on the user's PC as new messages, delete them from the server, and then disconnect.

Other protocols, notably IMAP, ( Internet Message Access Protocol ) provide more complete and complex remote access to typical mailbox operations.

Many e-mail clients support POP as well as IMAP to retrieve messages ; however, fewer Internet Service Providers ( ISPs ) support IMAP.