Brent Simmonds is a Mac developer and there's been a discussion about the Mac email client landscape brewing for a while. The Coccoa requirement is due to the

Brent Simmonds is a Mac developer and there's been a discussion about the Mac email client landscape brewing for a while. The Coccoa requirement is due to the unstated context that we're talking about an email client for Mac OS X. By shipping Mail with every Mac, Apple basically makes it impossible for someone else to come along and compete with a commercial product. Thunderbird, while a fantastic piece of work, doesn't behave quite like a Mac-native application. By saying it's got to be Coccoa, Brent's saying it has to be through-and-though Mac-like.