Initially changed my security preferences to below have been Unable to receive or delete emails even from Trash:
I also cannot shutdown computer so have to manually shutdown.
require password to wake up this computer ...
Disable automatic login
Log out after 30 minutes ...
set up a master password
FileVault protection is Off for this account since I don't have enough capacity to set up
Unlocked below but still no difference:
Require password ...
Log out after ..
Have been Advised to either back up/make copy of my messages and reinstall Mail application or take to a Mac store Genius
Retrieving data ...