POP3 : Java Glossary

POP3 (Post Office Protocol version 3). The protocol most commonly used for fetching mail from a server. Some POP3 servers can also be used to send mail. The advantage of POP3 for sending over SMTP (Simple Mail Transfer Protocol) is it will work even if you come into pick up your mail via a foreign ISP (Internet Service Provider). Further, it has better authentication. It is described in unusually clear language in RFC 1939.

POP3, out the box, does not let you find out who a message is from and sample just some of the message before committing to downloading the whole thing from the mail server. The optionally-supported TOP command rectifies that oversight.