A free mail checking program with many nice features.

CheckP3 Features
Secure Full support for POP3 password authentication, using CRAM-MD5 (rfc2195) or APOP (rfc1939), for IMAP password authentication using CRAM-MD5 (rfc2195), and for HotMail HTTPMAIL encrypted passwords via Digest MD5 (rfc1321 and rfc2069). Support SSL !!!!!!!
Unlike CheckP3, many other email checkers can't encrypt your email password and so they become a security risk.
SPAM aware antispam with Regular Expressions (REGEX)
Easy to setup Automated Windows installer.
Easy to use Multiple window interface, online help.
Versatile Check POP3/IMAP/HotMail(TM) email accounts, newsgroups, FTP sites, or even files on your hard disk. Check if a server is up (PING), show statistics about your network hardware, synchronize the PC clock with Internet time servers.
Automated Launch user-defined programs when new messages are received. Automatic or manual checks with debug mode,...
Well-connected Firewall and proxy support... Send email...
Customizable Dock to desktop, set window transparency (win2k/xp), personalized layout.
Compact Minimum HDD and RAM requirements...
Fun Wav support, MS Agent support...
International English and Italian, with translation toolkit to add more languages.