Can't Get There From Here
I've been using either Mozilla email or Thunderbird for some time now but have found an area they are lacking. Namely, exporting. If, for example, I want to export all of my email so I can store it while reformatting my hard drive I'm left up the creek without the proverbial paddle. Neither Mozilla email client can export email. So what are you supposed to do? I don't know. Copy the folders?
Drop me a line if you know of a way of exporting then importing back in. By they way, after using both for awhile, I think Thunderbird runs better. YMMV. FWIW.
Aloha!