I have no idea why but the latest version of Thunderbird for OS X has started crashing on me 4-5 times a day. So instead of searching for something else I decided to just try out Apples own mail client Mail. I had used it briefly when I first shifted to OS X and was quite impressed but as I already was using Thunderbird I stuck with what I knew. The main problem was going to be moving my mail, but a bit of googling provided the solution, get the file from the profile called Inbox with no file extension copy it to your desktop and give it an .mbox extension, navigate Mail to it, and away you go. Easy. On importing it I found I had over a 1200 emails, maybe that was the reason Thunderbird wasn’t happy!! Only problem I have found with Mail so far is the lack of adding a decent signature, maybe it will work with HTML. I hope so!!!