The release notes contain a huge list of new features and improvements including a new email search with advanced filtering options, global search with autocomplete, smart folders, tabbed email messages, new add-ons manager, improved address book, better Gmail integration and integration into Windows Vista’s search results.

Improvements have been made to overall performance and stability as well as web compatibility and sustainability. The way IMAP connections are handled has been improved in this version of Thunderbird as well. Thunderbird can now download IMAP messages by default in the background “to allow for faster message loading and better offline operation”.

Users who are interested in the new version can download it from the Mozilla Thunderbird website. The usual precautions should be taken considering that this version is still a beta version that should not be used in a production environment. The full release notes can be accessed at this link.