But it goes back to Leopard, stayed in Snow Leopard, and continues in Lion.

hmmm...seems like a bug or something...

But the Mail app, as I understand it, is all new in Lion. By logic and not any understanding of deep computer workings, that would tell me some other app is at work. Maybe the subroutine that engages the internet to check for mail?

. . . . just having a slightly new interface and a few new features? If that's the case, then that's consistent with the issues I continue to experience.

I don't know if that causes the problem...hhmmm...I thought it was the Mail software.

Check all your settings in prefs.

Force quit is something you do if the application is "not responding." (i.e. crashed)

If it is saying that mail "canceled" shutdown that means mail is probably still doing something that it needs to finish (maybe you have unsaved changes?) and the system needs you to "regular" quit mail before you can shut down.

yeap....i am also into this...some times need to force quit mail app. Probably a bug of Lion....i've reported it by the way to Apple.

Φαψεβοοκ

It happens in Lion...

lion hosed up my email big time.