POP3

The Post Office Protocol, version 3

RFC:1939 (may have been obsoleted in the meantime - haven't checked)
FreePOPs - an anything-to-POP3 proxy that supports Gmail and a gazillion webmail services via lua scripting.

Python	Microsoft Exchange Server	An update on my RSS setup	The IMAP Protocol
Lua	If I Were a Fly...	Gmail	Notes:
HOWTO: Read .Mac Mail on a SonyEricsson Phone	RSS	Mail.app 0.2	Cursory Notes
Xmas Phones	Introduction	Russell on Communicontent	Nokia 9500
POP3	SonyEricsson T610	Notes On The Z1010	Neat Ideas
Gmail	Treo 600	The SSL Way, and Why Mozilla Needs a Push	Perdition
Think Different	VersaMail