21Nov Mail.app Consistently Crashed. Culprit Found.
Mail.app recently started to crash within two seconds of getting launched. I thought there was a corrupt email so I deleted most, but that did not solve the problem. I next tried deleting plist and junk/deleted items but that didn’t fix it either. Doing a Google search didn’t bring up any helpful results but I did find this thread on the Apple Discussion Boards.
The culprit behind the crashes was Safari 4 (I had installed the developer preview a few weeks back). Following the instructions left by a member at the thread mentioned above, I uninstalled Safari 4 which reverted the app back to version 3.1. Next, I ran software update to get version 3.2. End result: no more crashes.