HT1338 Mail does not open after software update?

My MacBook just updated with OSX 10.6.8 buildK549.  Now my Mail does not open. I get a message that the mail version 4.5  1084/1065 is not compatible with the OSX.  There was a new mail icon in the apps file but it did not open. Any suggestions?
How do I reinsatll Mail?

It's giving you that message because the update changed Mail from version 4.5 to 4.6 and it's seeing the 4.5. The part of the update that was meant for Mail failed because it couldn't find Mail where it was looking for it.