Five solid replacements for Microsoft Outlook

Thunderbird

Thunderbird is one of the best of the alternative email clients. It benefits from the strength of Firefox, and it provides plenty of add-ons, a great migration assistant, a powerful address book, an attachment reminder, and lots of built-in security features.

Thunderbird

Thunderbird is one of the more stable email clients available, and it's cross platform and user-friendly. Plus, it is possible to connect Thunderbird to Exchange.

Zimbra Desktop

Zimbra Desktop offers a unique take on the desktop email client. Although you won't be connecting Zimbra to an Exchange server with ease (there are reports that it is possible, though), you can connect it to many other services.

One feature that sets Zimbra apart is its ability to connect to social networking sites, such as Facebook and Twitter. It can also connect to Mail, Hotmail, Gmail, Yahoo, and a number of other third-party email hosts. The interface takes getting used to, but once you "get" Zimbra, you'll find it quite powerful and useful.

Claws Mail

Claws Mail is one of the fastest, most configurable email clients available. You won't be connecting Claws Mail to an NTLM-based Exchange server any time soon (or maybe ever). But if you don't need Exchange support and you're looking for an alternative email client that can do just about everything else, Claws could be just what you need.

Claws Mail

Claws Mail is friendly enough for new users, but it also offers tons of features for power users. It has a good number of plug-ins, along with a great configuration tool, one of the fastest start times of any email client, multiple MH folder support, Mbox import/export, an external editor, built-in GnuPG support, and support for SSL over POP3, SMTP, IMAP4rev1, and NNTP protocols.

eM Client

eM Client is fully optimized to run on Windows XP, Vista, and Windows 7. It can connect to third-party POP/IMAP servers, like Hotmail, Yahoo, and Gmail, and import from other email clients.

eM Client

eM Client offers a full-featured calendar that can sync your Gmail calendar or your mobile device. Messages can be tagged, searched, and  filtered with an interface that's easy to navigate. eM Client also contains a powerful tool that lets you share contacts with other users, and it can Sync your Google contacts. You won't be connecting eM Client to Exchange, but you will enjoy a feature-rich, easy- to-use email client.

Pegasus

Being one of the oldest email clients on the block has its advantages. Pegasus Mail enjoys an incredibly rich community and a stability not found in other clients. And unlike some other email clients, Pegasus Mail has a rigid adherence to standards.

Pegasus Mail

Pegasus Mail claims that it will protect you from even the worst HTML-borne viruses and exploits. That is a bold claim, but one it can back up.

Pegasus Mail can't connect to Exchange. But if you don't use Exchange and you want an email client that will help prevent infection from HTML-mail sources, Pegasus Mail might well be the solution.