Can I make Apple Mail use "m" as the "mark unread" hotkey? I'd like to make "m" the hotkey for marking emails unread, since that's the same key as every other email or RSS application uses, and command+shift+u is unwieldy. The only place I can find to set this is the global hotkeys and it won't let me use unmodified keys (presumably because that would break things). Is it possible to do this?
You can do the following:


Go to System Preferences > Keyboard > Shortcuts
click App Shortcuts and add a new shortcut using the "+" button
Select Mail from the list of your applications
As Menu Title, you have to put the exact name of the menu command you want to add. In your case, it should be "As unread"
Choose the shortcut you want
Just Add the modification


After these steps, just restart Mail and it's done. You can check on the menu bar to see that the shortcut has been modified.