Following an internal email leak, Mitchell Baker, Mozilla Foundation Chairwoman, has announced that Mozilla will make no further investments in evolving Thunderbird, its open source email client. Instead, future releases will only carry security and stability updates.
As for any other open source project, this doesn’t mean Thunderbird is coming to an end (though it usually looks a lot like that) as Mozilla is also committing to support ongoing and future community efforts to evolve the product, which sounds pretty similar to the SeaMonkey strategy.
As you may recall, SeaMonkey, the original Mozilla Internet Suite, was abandoned by Mozilla Corp. and successfully taken and driven by the community since then. Mozilla Corporation still provides infrastructure for developing, building, and distributing it to thousands (if not millions) of enthusiastic users.
I believe the problem for Thunderbird (and its drivers) was finding a way and designing a messaging product that didn’t overlap with Firefox, since most online messaging happens on the web nowadays. So most ideas to expand Thunderbird from an email to a messaging product (which was a Mozilla Messaging goal) collided with Firefox future: device enabled, WebRTC, mobile, Social API, and so on.
The other possible and, to some degree, natural path for Thunderbird, was becoming a full featured productivity tool but this has no room within Mozilla’s mission. How exactly do integrating calendar or instant messaging capabilities into Thunderbird help advance the Internet? The lack of an answer to this question may be the main reason why these promises haven’t come true yet.
To summarize: Thunderbird is a mature email client, and becoming more than that is out of scope for Mozilla. Still, Thunderbird is not dead, just as SeaMonkey isn’t and won’t be in the foreseeable future. It is also a gigantic opportunity for an entrepreneur to grab the code and make the smashing productivity suite many users are craving for.