Mozilla has announced the availability of the first Thunderbird 3 beta release. This version introduces some significant user interface improvements to the e-mail client, along with some very good IMAP optimizations.

Tabbed interface



The most visible enhancement in the beta release is the new tabbed user interface. When we looked at alpha 3 in October and wrote about some of the prominent upcoming features on the short-term roadmap, we pointed out that tab management and session restore were in the works.

In the beta release, users can open mail folders and individual messages in new tabs. The tabbing system is also exposed through Thunderbird's extension API so that third-party add-ons can take advantage of the feature. The latest nightly builds of Lightning, a calendaring extension for Thunderbird, allow users to display the calendar and task list in separate tabs. The new tab bar interface, which is modeled after the one in Firefox, has an overflow menu at the end but doesn't appear to allows tab reordering yet.

Mozilla user experience designer Bryan Clark has written several blog entries about the new tab feature in which he explains the thought process behind some of the design decisions.

Cribbing from Firefox

Developers have also continued their efforts to reorganize the message interface and move message-related features out of the toolbar and into the message pane. In the last alpha release, they put "reply" and "forward" buttons next to the address section of the message pane. They also made it easier to add contacts to the addressbook with a new single-click star system that was inspired by the new Firefox bookmark system. In this release, these interface behaviors have been further refined.

Another user interface feature that the Thunderbird developers have cribbed from Firefox is the improved add-ons manager which has a built-in search tool for finding and installing popular extensions.

One of the improvements touted by the developers for this release is enhanced support for importing mail from other clients. They have added the ability to import from Apple's Mail client and made several other improvements. During my testing on Linux, however, I was not able to import much of anything. The only option supported on Linux is importing from Communicator 4.x. To get my mail from Evolution into the Thunderbird beta, I had to dig into Evolution's directory structure and copy the raw mbox files over into Thunderbird's directory structure. Thunderbird was also unable to import my addressbook because it still can't read vcard data.

Lack of support for importing data from other programs is the biggest weak spot that I found in this beta release. The problems I encountered with the import system are especially ridiculous in light of the fact that Thunderbird is fully compatible with the mbox and vcard formats and uses both of them internally. The program is obviously still a work in progress, so it's likely that many of these issues will be addressed before the final release.

Platform integration is an important area that is beginning to receive a lot of attention from the Thunderbird developers. In this beta release, Thunderbird will use the system addressbook on Mac OS X and will also display notifications with Growl, a popular notification system that is widely used by third-party Mac applications. On Windows Vista, Thunderbird will integrate with the platform's search and indexing system. Tighter Linux integration is coming, too. We also recently looked at some ongoing theming efforts that aim to bring the native look and feel of the GNOME desktop environment to Thunderbird.

Future plans



David Ascher, the former ActiveState CTO who was brought in to lead the Thunderbird effort when the project was spun off by the Mozilla Foundation last year, has written a detailed blog entry about the status of development and some of the future plans.

"[W]e've moved the product forward, in part thanks to new capabilities in the underlying Mozilla platform, which gives us faster performance all around," he wrote in a blog entry. We're definitely not done making feature changes, including some pretty significant feature work that we expect will be integrated in Thunderbird 3 in later beta releases, some features that will live as optional add-ons, and some experiments which may end up in later releases of Thunderbird or not, depending on the result of the experiments."

Some of the experimental projects that he describes are very intriguing, including a tile-based addressbook view, a threaded conversation view for messages, AwesomeBar-like autocompletion for contacts, and tighter integration of the Lightning calendar extension.

The agenda is quite ambitious and it offers a laundry list of killer features that could give Thunderbird an edge over competing mail clients... if any are ever fully implemented. The developers are clearly working harder to leverage the underlying strengths of the Gecko engine in order to bring richer capabilities to the application. The experimental projects also reflect a growing willingness to adopt unconventional user interface concepts that are more closely aligned with browser-based mail clients.

Although there is still plenty of work to be done, development is moving at a good pace. The project is clearly gaining momentum and it seems like a lot of great ideas are on the table for Thunderbird 3. The new beta is available for download from the project's official web site. For more details, check out the release notes.