Apple mail auto fill not working

Question

Since upgrading to Mountain Lion auto fill is no longer working when addin email addresses to an email. I have checked preferences and it is turned on. Additionally when I start to type the spinner, for lack of a better term, starts to spin but it never fins an address to auto fill. Any idea why this may be happening?
Thanks,
Mike

Answer 1

Please follow these directions to delete the Mail "sandbox" folder.
Back up all data.
Quit Mail.
Triple-click the line below to select it:
~/Library/Containers/com.apple.mail
Right-click or control-click the highlighted line and select
Services ▹ Reveal
from the contextual menu. A Finder window should open with a folder named "com.apple.mail" selected. If it does, move the selected folder — not just its contents — to the Desktop. Leave the Finder window open for now.
Relaunch Mail and test. If the problem is resolved, you'll have to recreate some of your Mail settings. You can then delete the folder you moved and close the Finder window. If you still have the problem, quit Mail again and put the folder back where it was, overwriting the one that may have been created in its place. Post your results.
Caution: If you change any of the contents of the sandbox, but leave the folder itself in place, Mail may crash or not launch at all. Deleting the whole sandbox will cause it to be rebuilt automatically.