Most Mac users default to Apple's good-but-not-great Mail program to manage their e-mail. But given Mail's serious deficiencies (e.g., weak to nonexistent integration with calendaring and contacts), a variety of open-source initiatives are underway to bring a full-featured e-mail client to the Mac.
That's the good news.
The bad news is that there appears to be little to no coordination between the different groups, leading to duplication and fragmentation of efforts.
Zimbra, Mozilla Thunderbird, Mozilla Raindrop, and a new project initiated by NetNewsWire founder Brent Simmons, Letters.app, all seem to be heading in the right direction. But they're taking different roads and seem intent on reinventing the e-mail wheel.
Why not band together?
There seem to be a number of good reasons. Zimbra, for its part, is geared toward the enterprise messaging market. It's also licensed in such a way that it's unlikely to be palatable to competitive efforts, given that it requires developers to include Zimbra logos and other trademarks in the UI of the derivative work.
As for Mozilla's Thunderbird, while its browser cousin, Firefox, continues to expand its market share due, in part, to its active and enthusiastic developer community, Thunderbird still has a nascent community. So does Raindrop, Thunderbird's younger and nimbler sibling.
With a still-small community, there's less reason to accept the other trade-offs that come with building on the Thunderbird or Raindrop source code.
Those trade-offs may well be significant.
For example, Mark Mason, a Thunderbird user and Letters.app developer, argues that "it would be much more work to fix up Thunderbird than start from scratch."
There's also the potential problem, pointed out to me by Dj Walker-Morgan, that Thunderbird is not a native Cocoa (Mac) application and doesn't integrate seamlessly with the Mac OS X interface," an issue acknowledged by Mozilla's messaging head, David Ascher ("[Letters.app's] primary focus on OS X is a real difference").
I say "potential problem" because Thunderbird's cross-platform approach to e-mail (i.e., it works equally well on Mac OS X, Windows, or Linux) is.
After all, most of us don't have the luxury of spending 100-percent of our time on just one platform, be it Mac, Windows, or Linux (or any of the myriad of mobile devices out there.)
Such thinking doesn't sway the Letters.app crowd, which has the stated goal of creating "a lean and programmable IMAP e-mail client, with plug-in and automation APIs, designed for developers and power users." Given this goal, building from cross-platform Zimbra or Thunderbird simply may not work.
Even so, Ascher remains "hopeful that there'll be room for collaboration in places, and cross-pollination." I do, too. The Letters.app community is energetic and has attracted some significant names from the Mac community, including John Gruber and Gus Mueller. These would be great people to help build a next-generation e-mail client.
The Mac definitely needs one. And the Letters.app community could well be the ones to build it. But it would be ideal to combine the talents of it with other open-source e-mail communities working toward that goal, rather than fragmenting their efforts.
This might not mean a sharing of source code, but perhaps it could mean a sharing of ideas, techniques, and even a common standard for add-on extensions?