In System Preferences -> Keyboard -> Keyboard Shortcuts -> Application Shortcuts (Mail.app) I have set up ⌘+Enter to send mail. It works great...until I use certain Mail commands. For example, if I use Shift+⌘+H to view the full headers of a message, the next time I try to use ⌘+Enter to send a mail it doesn't work. I have to quit Mail and then when I restart ⌘+Enter works again. Same thing happens if I use Shift+⌘+B to bounce a message. I can duplicate this every time so it's not an intermittent bug. It's a minor annoyance, but I wonder if anyone else can confirm it happens to rule out that it's something specific to my Mac. I'm on OS X 10.6.4. Thanks!