Why Not?

I recently restored my macbook from a Time Machine backup and ran into the following error whenever I tried to start Mail.app:

Error: This version of Mail (4.0, 1075/1076) is not Compatible with Your Version of OSX (10.6.1)

The reason for this is that the data associated with the 10.6.1 update for Mail.app did not get applied when i restored from the backup. To solve this error download and install the following patch from Apple:

http://support.apple.com/kb/DL930