I'm considering switching to Airmail from Mail.app. I see the method you have for importing individual email boxes / folders in one by one...but I have hundreds of boxes (I'm a freelance graphic designer and each project gets it's own folder within a client's subfolder.) I'm sure i'm not the only one with hundreds if not thousands of folders. A simple import to bring them all in would be a workable option for switching to Airmail. The idea of doing it one folder at a time is a bit of a deal breaker.