Windows XP look, 128-bit Encryption support, Junk Mail filtering...
New in v6.0: New security features for protecting your computer from harmful e-mail and blocking potentially harmful attachments, "Windows XP look and feel" (new stylized buttons in the toolbar and more colorful menu background and toolbar areas) Upgrade Meter: 5
New in v5.50: Built-in 128-bit Encryption support (no need to download separate patch), performance enhancements, packaged with Internet Explorer 5.50 Upgrade Meter: 5
New in v5.0: New starting page, Junk Mail (SPAM) filtering system, new "block senders" filter, contacts pane (with integrated Windows Address Book), identities for multiple users, offline support (download news and IMAP folders) and message synchronization, support for multiple signatures, phone dialer integration, advanced Internet directory search, HTML source editing, customizable message filters, customizable toolbars, watch/ignore thread options, Stationery wizard, improved message storage, auto-detection of your connection state; Release Notes Upgrade Meter: 5
Pros: Extremely ease to use, impressive feature-set, advanced security, freeware
Cons: Lacks Outlook's PIM, calendar, and journal functions and "Outlook Today" feature