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Bring up a terminal and check to see if it's still running. In the terminal type:

ps -ef | grep Mail | grep App

If you get anything returned, it will look like this:

501 5152 133 0 7:09AM ?? 0:07.54 /Applications/Mail.app/Contents/MacOS/Mail -psn_0_3949508

The process id (pid) is the 2nd field on the information returned, has been highlighted in the line above, and it's what you want to kill:

kill 5152

Once done run the "ps" command again. If that returns information again, change the "kill pid" to "kill -9 pid".

$0.02 worth.
 
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