View source for POP3 (en)

'''POP3''' (''Post Office Protocol version 3'') is a [[protocol]] used to retrieve [[email|electronic mail]] (email) from an [[server|email server]].

This protocol is closely related to the [[SMTP]] protocol, where the [[SMTP]] protocol is useful for sending electronic mail from the sender's computer to the [[server]].

The [[POP3]] protocol was created because the design of the [[electronic mail]] system requires the existence of an [[email server]] that temporarily holds [[electronic mail]] until it is retrieved by the rightful recipient. The presence of an [[email server]] is due to the fact that only a small fraction of computers receiving electronic mail are continuously connected to the [[internet]].

This protocol is specified in [[RFC]] 1939.

== Example transaction ==

 S = server
 C = Client

 C : (initialize connection)
 S : +OK
 C : USER wikipedia
 S : +OK
 C : PASS indonesia
 S : +OK wikipedia have 2 messages (320 octets)
 C : STAT
 S : +OK 2 320
 C : LIST
 S : 1 150
 S : 2 170
 S : .
 C : RETR 1
 S : +OK 150
 S : --email data--
 S : .
 C : DELE 1
 S : +OK
 C : QUIT
 S : +OK Bye

== Related Protocols ==
* [[SMTP]] protocol for sending electronic mail
* [[IMAP4]] a protocol similar to POP3, but with more comprehensive facilities

== External links ==
* [http://www.faqs.org/rfcs/rfc1939.html RFC 1939] Post Office Protocol - Version 3