Mozilla Messaging has announced the release of Thunderbird 3.1, a minor update that brings performance improvements, bug fixes, and some new features.

The most significant enhancement in 3.1 is the new Quick Filter bar, which makes it easy to filter and search the contents of the current folder. It has several icons that you can click to filter for messages that are unread, starred, sent by a contact, or have an attachment. It also has a search box that will allow you to find messages in the current folder.

In the previous version of Thunderbird, the global search box offered a separate mode that was accessible from a drop-down menu for searching the current folder rather than the entire message database. The new search feature in the Quick Filter bar replaces that feature and makes it more discoverable. The filter bar resets when you switch folders, but you can click the "pin" icon to keep the filter settings in place as you switch.

I used to add a View combobox widget to the toolbar so I could see unread messages in some high-volume mail folders, but the new Quick Filter bar provides much more convenient one-click access to the same functionality. It's a nice addition to the client, but I'm not totally sold on the user interface yet. Having two search text boxes in the window is a little awkward. The Quick Find bar looks a bit sloppy on Linux due to the use of inconsistent icons and an oddly-colored top border.

Some other features introduced in this release include a new migration assistant tool to help Thunderbird 2 users retain their desired settings. There is also a new Saved Files Manager (based on the Firefox download window) that allows you to manage attachments and other downloaded content. Message indexing and search got a performance boost and are a bit snappier in the new version.

Thunderbird 3.1 is available for download from the Mozilla Messaging Web site. For more details, you can refer to the official release notes.