It looks like a nice client- What are it's distinguishing features? What needs help? What are your intentions now- To throw it out there, or keep building it?
Are there binaries?
How are you handling the Messages in-memory? I'm looking for a mail client that can handle my multi-hundred-thousand email inbox, but everyone except Mulberry tends to have a problem ;)
Looks really sharp. Kinda reminds me of FF with the tabs at the top.