Thunderbird

Thunderbird is a great email client from the same people who brought you the Firefox browser. Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts.

Keep Your Vital Information Organized
Advanced Folder Views
Message Tagging
Message History Navigation
Improved Search
Saved Searches
Easy Access to Popular Web Mail Services
Phishing Protection
Privacy
Cutting Out the Junk
Outfit Your Inbox
Message Templates
Add-ons Manager for Extensions and Themes

Is a good email client from Mozilla.Is a modern alternative to outlook Express.The design is better , but the functionalities are in the most of the cases the same.Add a new account and set the proxy configurations (SMPT,POP3 options).Compose message window have more options and you have access more fast to all the options.