By now you’re thinking “What? How the Hell™ did this happen? I never touched my copy of Mail. I never did anything to it besides install the updates that you offered me!”
Alas, whatever you did or didn’t do, Mail wont launch.
Some of you may have thought “Run Software Update”. That may not work.
Some of you may have thought “Re-apply last Combo Updater and let Installer work it out for you.” Well, I didn’t think of that. But I did try copying just the Mail.app from a known-good mac across to the non-working one. That also didn’t work. Why? The version seems to be correct— in my case it was Mail 4.5 on OS X 10.6.8.
Let’s get to the nitty-gritty.
Here is where the file lives that has gone south:
I have Developer Tools installed so I used Property List Editor to open it. It’s just an XML file so you could use your favorite text editor.
So what we are looking for is Bundle version, string, short. The faulty one was 4.3, I replaced it with 4.5. The Bundle version and ExpectedMailVersion were both at 1081, so I changed them to 1084.
This file must be edited as root. So, either login as root, or use the sudo command if you are using the Terminal to launch your favorite editor, which is of course vi and definitely not emacs.
Voila! Mail launches now.