- New ability to search the Web.
- Improvements to email search.
- And several other platform fixes.

- Fixed Bugs.

- Thunderbird is based on the new Mozilla Gecko 9 engine.
- New opt-in system for users to send performance and usability data back to Mozilla to improve future versions of Thunderbird.
- Additional support for Personas in the compose and address book windows.
- Better keyboard handling for attachments.
- Windows users can hide the menu bar (and show it with the "alt" key).
- Several user interface fixes and improvements.
- Fixed several security issues.

- Thunderbird is based on the new Mozilla Gecko 8 engine.
- Add-ons installed by third party programs are now disabled by default.
- New Search and Find Shortcuts.
- Improved accessibility of the attachment list.
- Folder switching pane widget removed.
- Numerous platform fixes to stability.
- Fixed several security issues.

- Thunderbird is based on the new Mozilla Gecko 7 engine.
- Several user interface fixes and improvements.
- Several fixes to attachment handling.
- Ability to print a summary of selected email messages.
- Platform improvements to Address Book.
- Fixed several security issues.
- Numerous platform fixes that improve speed, performance and stability.

- Fixed Bugs.

- Fixed Bugs.

- Thunderbird is based on the new Mozilla Gecko 6 engine.
- Several theme improvements for Windows 7.
- Support for Windows 7 Jump lists.
- Several fixes when importing email from Microsoft Outlook.
- Various other user interface fixes and improvements.
- Numerous platform fixes that improve speed, performance, stability and security.

- 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.
- Over 390 platform fixes that improve speed, performance, stability and security.

- Several fixes to improve performance, stability and security.

- Several fixes to improve performance, stability and security.

- Prevents a crash after update, that is affecting some users.

- Several fixes to improve performance, stability and security.

- Several fixes to improve performance, stability and security.
- Several fixes to improve handling of large folder files stored locally.
- Several fixes to improve corruption in local copy of IMAP mailboxes.

- Fixes a critical security issue that could potentially allow remote code execution. This issue does not affect email or newsgroups but could be triggered through browser-like features or add-ons. 

- Several fixes to improve performance, stability and security, see the Security Advisory.
- Several fixes to improve the user interface and add-ons experience.

- Several fixes to improve stability.
- Several fixes to improve the user interface.

- Fixed Bugs.

- Several fixes to improve stability.
- Several fixes to the user interface.

- Several fixes to improve stability and security.
- Several fixes to the user interface.

- Faster Search Results. Message indexing is faster and provides users with faster search results.
- New Quick Filter Toolbar lets you filter against search terms, tags, starred messages, address book contacts, new emails, and attachments.
- The new Migration Assistant gives Thunderbird 2 users a way to choose the new features in Thunderbird 3.1 or to keep their current features and settings.
- New Saved Files Manager displays all the files you downloaded from your email to your computer.
- Mail Account Setup Wizard.
- Improvements to Stability, Memory, and Password Handling.

- New Search with Advanced Filtering Tools.
- New Global Search Field with Autocomplete.
- New Mail Account Setup Wizard .
- Redesigned Mail Toolbar.
- "Smart Folders".
- New Message Summary View.
- Message Archive.
- New Add-ons Manager.
- Improved Address Book.
- Improved Gmail Integration.
- IMAP Folder Synchronization.