Since a few days, I finally finished the transition to ML on my three macs (DT in the office and at home, and a MBP). Update to 10.8.2 done.
On all three machines, Mail.app displays an "unexpected Quit" when I quit the program. In can upload the crash report if someone would be willing to help me "reading" it.
I use the "classic layout", and I have always two viewer windows open to allow easy access to two mailboxes in parallel. My mailbox is pretty large, there are 6 accounts to receive mail, and quite some rules.
Suggestions welcome! BW