Mozilla will roll out the newest version of its open-source e-mail application, Thunderbird 3, in mid-November. Supposedly, Mozilla made over 2,000 improvements to the platform, although users are most likely to notice its more top-line features such as filtered search and tabbed e-mail.

Thunderbird 3, which will be available from this site on its release date, is compatible with Windows, Mac OS X and open-source platforms. As with Firefox 3.1, Thunderbird 3 is built on the Gecko 1.9.1 rendering platform, lending the e-mail platform the same security enhancements and Web Standards support as the Firefox browser. Also on the security front, Thunderbird will notify users of security updates and automate the download and installation process.

Features new in Thunderbird 3 include:

• Filtered Search: As with the majority of e-mail services, Thunderbird 3 allows users to search their e-mail for particular terms. Thunderbird's search results page offers a variety of filters so that users can further pinpoint the exact e-mail they need, as well as a timeline showing how often a particular search term has occurred.

• Tabbed E-Mail: Taking a page from Firefox and other browsers, Thunderbird 3 offers the ability to load e-mails in separate tabs, as opposed to opening new windows, in the process reducing desktop clutter.

• One-Click Address Book: Clicking on the star icon next to incoming messages will send the email sender's data to the address book.

• New Mail Account Setup Wizard: Mozilla has attempted to streamline the setup process by limiting the amount of information that new users will have to input. Instead of requiring that the user input IMAP, SMTP and SSL/TLS (Secure Sockets Layer/Transport Layer Security) settings, Thunderbird 3 will attempt detect those automatically.

On top of that, Thunderbird 3 will include a streamlined message archiving system, "smart folders" that allow users to view e-mails from multiple accounts without needing to sign into those accounts, an add-ons manager for customization and deeper integration with Gmail.

Although Mozilla's developers committed a considerable amount of time to Thunderbird and incorporated a good deal of user feedback into the newest version, the group is more well-known among both the tech community and the general public for its Firefox Web browser. Since its release in 2004, Firefox—now provided by Mozilla Corp., a subsidiary of the Mozilla Foundation—has expanded to become the second-most popular Web browser in the United States, behind Microsoft Internet Explorer and ahead of Apple Safari and Google Chrome.

Firefox has been cited by analysts for multiple security flaws, but the organization and its developers have generally moved quickly to issue patches in order to cover those flaws. Throughout 2009, Firefox has issued updates to plug critical security holes. At the same time, it has also worked to fix bugs cropping up in Thunderbird.