Mozilla has announced a new plan for the ongoing development of its Thunderbird email client that it says will provide for a stable product and continued opportunity for innovation

That's all well and good, but the contents of a leaked internal Mozilla memo suggest that the full picture may be less rosy than it seems.

The announcement, which was made in a blog post by Mozilla Foundation chair Mitchell Baker on Friday afternoon, suggests a major restructuring of the release and governance model of the Thunderbird project:

Once again we've been asking the question: is Thunderbird a likely source of innovation and of leadership in today's Internet life? Or is Thunderbird already pretty much what its users want and mostly needs some on-going maintenance? Much of Mozilla's leadership – including that of the Thunderbird team – has come to the conclusion that on-going stability is the most important thing, and that continued innovation in Thunderbird is not a priority for Mozilla's product efforts.

It's not hard to see what she's getting at. "Continued innovation in Thunderbird" means the process of adding new features and UI improvements. That's out. "Ongoing stability", on the other hand, means bug fixes and security patches, which are all that current Thunderbird users should expect from now on. And given the slow pace of Thunderbird development today, it's safe to say that Mozilla is set to scale back its efforts on the project from "some" to "virtually none".

So does that mean Thunderbird is dead? No, it's just resting. Mozilla has posted additional details of its plan on a wiki page. Read on:

In order to manage these two perspectives, we are proposing to adapt the Thunderbird release and governance model in a way that allows both ongoing security and stability maintenance as well as community driven innovations for the product.

See? It's got beautiful plumage. Thunderbird will still innovate, but from now on, any innovation will be strictly "community driven". In other words, Thunderbird is set to become yet another open source desktop application that's tossed over the wall by the company that built it, in hopes that some eager volunteers will pick it up and polish it into world-class software.

That almost never works. In fact, Baker admits in her blog post that generating enthusiasm for Thunderbird among developers has been near impossible:

We've tried for years to build Thunderbird as a highly innovative offering, where it plays a role in moving modern internet messaging to a more open, innovative space, and where there is a growing, more active contributor base. To date, we haven't achieved this.

What's more, the contents of what appears to be an internal Mozilla memo, marked "confidential" and leaked to El Reg by an anonymous source in advance of Mozilla's announcement, suggest there's more to this plan than a simple rearranging of the deck chairs.

We can't be certain the memo is genuine, but it includes wording substantially similar to Baker's blog post and the Mozilla wiki page. Where it talks about the move toward "community-driven innovation", though, the memo adds this tidbit:

This will mean an eventual shift in how we staff Thunderbird at Mozilla Corporation – we are still working out details, but some people will likely end up on other Mozilla projects.

Just how many people make "some" is hard to judge. As recently as 2007, Mozilla employed just two full-time developers on the Thunderbird client – that is, until they quit. It's hard to see how a company could commit fewer developer resources to a project than that. (No. Wait. There's a way.)

Mozilla's plan says, "Mozilla will continue to provide paid staff, logistics and infrastructure for the release drivers team to produce updates and new releases with the same level of quality than today [sic]." That's not saying much.

Mozilla has always struggled to keep Thunderbird vital. In 2007, it spun off its email and IM developers into a new, independent subsidiary, Mozilla Messaging. That didn't seem to work out so well, however, and the parent foundation reabsorbed Mozilla Messaging in 2011.

Part of the problem is that standalone desktop email clients such as Thunderbird have largely fallen out of favor. Thunderbird may claim more than 20 million users, but Gmail alone boasts 425 million active users worldwide, and Gmail isn't the only web-based email service. In light of those numbers, developing Thunderbird probably hasn't been much fun for a while – and now, Mozilla has seemingly decided it isn't worth spending resources on.

Instead, Mozilla will concentrate its efforts on browser-based projects and offerings for the mobile market, such as the newly christened Firefox OS for low-end mobile handsets.

Mozilla's wiki invites questions and comments, and it says the plan will be refined throughout the summer, with the goal of hammering out "the final details" in September 2012. Current Thunderbird users have that long, at least, to shop for a webmail service. ®