POP

Post Office Protocol 3) A standard interface between a user's e-mail program and the mail server, defined by IETF RFC 1939. POP3 and IMAP4 are the two common mailbox access protocols for e-mail clients such as Outlook, Mail, Eudora and Thunderbird. POP3 is a simple system with limited selectivity. Incoming messages and attachments are downloaded when users check their mail. POP is typically configured to delete the messages on the server after downloading. If the user opts to not delete them, the messages will download again the next time mail is checked. See IMAP4, Internet e-mail service, SMTP and messaging system.