Microsoft’s Outlook is the big brother of Outlook Express, which is Window’s default desktop eMail client.

Outlook is part of Microsoft’s Office suite. It comes with a lot of extra features compared to Outlook Express, including time/event management, contact management, and Microsoft Exchange Server support to synchronize and share information.

Arguably, Outlook Express is a good enough tool for those who don’t expect a lot of flexibility from their software. But what if you want more without having to spend money? Which free alternatives to Outlook should you look into?

Thunderbird

What is it?

Thunderbird is Mozilla’s desktop eMail client. As such, it’s an open source application and supports various addons, which enhance its functionality.

Like Outlook, Thunderbird supports POP, IMAP, and SMTP. Using the Account Wizard, you also can subscribe to RSS News & Blogs, hook up to your Newsgroup account, and launch a quick Gmail setup.

What makes it a better alternative to Outlook?

Thunderbird is available not just for Windows, but also for Mac OS X and Linux. Localized versions of Thunderbird exist for dozens of the most common languages.

Thunderbird is much better than Outlook, in case you enjoy to customize your eMail client. There is a vast collection of themes and extensions available. These will also cover up for most features that are not integrated into Thunderbird by default.

Gmail

What is it?

Gmail or Google Mail is Google’s free webmail client.

Although it is only an online eMail application, Gmail is a very powerful tool that easily rivals most common desktop clients. Gmail supports POP and IMAP and it is fully integrated with the Google Apps suite.

What makes it better than Outlook?

The clear advantage of an online eMail client is its global availability. Wherever you go, whichever computer you use, your eMail is already there.

Gmail provides a complex selection of settings and features. Gmail tracks conversations and optionally compiles all eMails belonging to one conversation into a single thread. Within settings you can create filters, enable Google Mail Labs experimental features, manage multiple inboxes, and switch themes.

Zimbra Desktop

What is it?

Yahoo’s Zimbra Desktop is a desktop eMail client that rivals Gmail, Thunderbird, and Outlook alike. Interestingly, it is powered by Mozilla.

What makes it a better alternative to Outlook?

Much like its Mozilla companion Thunderbird, Zimbra is available in 20 different language versions for Windows, Mac, and Linux. The design is sleek and Zimbra offers several more theme options. Best of all, it’s easy and intuitive to use with a ton of useful features.

Zimbra supports its own online webmail client Zimbra as well as Yahoo! Mail, Gmail, Microsoft Live Hotmail, AOL Mail, Microsoft Exchange IMAP, IMAP, and POP.

Zimbra has a built-in calendar, contacts, task manager, documents, and briefcase.

Obviously, language integration is not yet perfect. Although I selected the US English language installation and confirmed this language preference within options, some tabs and menus are still displayed in the language of my operating system: German. This should not be an issue if you select the language of your operating system.

Zimbra synchronizes eMails, contacts, and calendars with Zimbra, Yahoo! Mail, and Gmail.

Like Gmail, Zimbra offers an optional conversation view, i.e. threaded conversations. It also comes with advanced tagging options.

Contacts can be grouped and tagged, you can add photos, and import/export via .csv files is supported.

Zimbra comes with great search features. You can quickly search your mailbox for all or specified item types or use the advanced search to add several search criteria, such as file size, date and time, tag, status, folder, and more. The best is that searches can be saved as virtual folders.

Zimbra extensions are called Zimlets.

For more details on how Zimbra compares to Outlook and Thunderbird, check out the Feature Comparison list.

What is your favorite eMail client and what makes it valuable to you?