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(messaging, protocol)
Version 3 of the Post Office Protocol. POP3 is defined in RFC 1081, written in November 1988 by Marshall Rose, which is based on RFC 918 (since revised as RFC 937). POP3 allows a client computer to retrieve electronic mail from a POP3 server via a (temporary) TCP/IP or otheronnection. It does not provide for sending mail, which is assumed to be done via SMTP or some other method.

POP is useful for computers, e.g. mobile or home computers, without a permanent network connection which therefore require a "post office" (the POP server) to hold their mail until they can retrieve it.

Although similar in form to the original POP proposed for the Internet community, POP3 is similar in spirit to the ideas investigated by the MZnet project at the University of California, Irvine, and is incompatible with earlier versions of POP.

Substantial work was done on examining POP in a PC-based environment. This work, which resulted in additional functionality in this protocol, was performed by the ACIS Networking Systems Group at Stanford University.

RFC 1082 (POP3 Extended Service) extends POP3 to deal with accessing mailboxes for mailing lists.
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(Post Office Protocol 3) A programming interface (API) from the IETF that enables a user's email program to access the mail server (RFC 1939 standard). Email clients such as Outlook, Mail, Eudora and Thunderbird are typically configured to retrieve mail either via POP3 or IMAP4, the other popular standard.

POP3 is a simple system with limited selectivity. Incoming messages and attachments are downloaded when users check their mail, and 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, email interfaces, SMTP and messaging system.

Incoming Mail Options
Most Internet mail services offer all three options. Users may choose IMAP if they need access from several computers or if they like to keep mail online indefinitely (see IMAP4).
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References in periodicals archive ?
* Enhanced Security for Business Mail Servers - Edge 8.6 expands on its POP3 traffic scanning ability by adding an SMTP proxy to scan inbound email traffic for customers who host their own email with internal SMTP servers.
Some steps are simple and easy to follow, while others (such as the POP3 setup instructions) could leave less technical users wondering what to do.
The product works with any standard POP3 application by integrating with it instead of operating as a separate program.
And then when you sign up for absolutely anything, only give your web based e-mail address and never your POP3 address.
Options include blocking ports and closing access to IRC chat and POP3 e-mail.
WebBox includes as a pre-configured Web (HTTP) server that supports multiple physical and virtual sites, a pre-configured e-mail system with SMTP and POP3 compatibility and browser-based interface, and an automated backup and restore system that supports disk and tape drives.
The two companies hope to release a product next year which will combine Sendmail's support for simple mail transfer protocol (SMTP) with MessagingDirect's implementations of post office protocol (POP3) and internet mail access protocol (IMAP4).
According to the company, DVQattest generates VoIP and videoconferencing calls with SIP signalling, synthetic HTTP, POP3, SMTP, DNS and DHCP transactions and a range of IP network tests.
From here, you're literally one click away from setting up Nokia's Messaging 3.0, which features support for both email (SMTP, IMAP4, POP3) Twitter and Facebook.
POP3 users can make use of the service for GBP0.50 per month per mailbox.