Thunderbird 5.0

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.

Tabbed email
An Archive feature similar to the one in GMail
Lightning fast search
Smart folders

Changelog:

More responsive and faster to start up and use
Thunderbird is based on the new Mozilla Gecko 5 engine
New Add-ons Manager
Revised account creation wizard to improve email setup
New Troubleshooting Information page
Tabs can now be reordered and dragged to different windows
Attachment sizes now displayed along with attachments
Plugins can now be loaded in RSS feeds by default
There are several theme fixes for Windows Vista and Windows 7
Support for Mac 32/64 bit Universal builds (Thunderbird no longer supports PowerPC on Mac)
Over 390 platform fixes that improve speed, performance, stability and security