migration assistant mac to mac email

Migration assistant is not moving over my email files.

More specifically: Mac A is an iMac in California running osx 10.6.8. It's been running Time Machine backups to an external drive. I stopped Time Machine, ejected the drive, shut down Mac A and moved to Maryland.

In Maryland there's Mac B, a Pro running osx 10.6.8. It was last used on October 1, 2011 and shut down. I started up Mac B, installed all software updates, and plugged in the external drive that I brought over from Mac A.

Ran Migration Assistant from a new temporary account with admin privileges. I asked it to move all files (i.e. checked all four boxes) from account X on Mac A to account X on Mac B (that is, the accounts have the same name). Seems like the Documents folder was transferred OK. But my email folders on Mac B contain nothing from Mac A ... its most recent contents are Oct. 1 2011.

What might be going on here? Do I have any other option except copying folders manually, and what other files might have been missed this way? As an example, I have thousands of photos that are managed by Lightroom, and I'm afraid to think of the headache ahead. Thanks!