All Mail.app messages (POP) gone and window will not open in new LION

Question

I have upgraded to Lion but now all my email messages seem to have disappeared. I have tried installing Postbox and using that. It works fine but Postbox cannot seem to locate my old email messages either.
I'd prefer to use the Mail.app but cannot right now. Any clues as to what might be causing this?
Thanks!!

Answer 1

You’re welcome.
Look for additional information that may be available in the form of error messages written to the Console:
1. Open /Applications/Utilities/Console.
2. From the File menu, choose either Open Console Log, or Open System Log, or both, so that Console displays the contents of both system.log and console.log.
3. Reproduce the problem and look at the bottom of the Console windows for messages that might be written there as a result.
<hr>
Do you have any Mail plug-ins? In the Finder, go to each of the following folders (if they exist). What do you see there?
/Library/InputManagers/
/Library/Mail/Bundles/
~/Library/InputManagers/
~/Library/Mail/Bundles/
To make accurately reporting this information easier, you may open /Applications/Utilities/Terminal, type the following command (you can just copy it here and paste it in Terminal), and press <Return>. You can then copy the output of that command from Terminal and paste it in your reply to this post:
ls -1 /Library/InputManagers /Library/Mail/Bundles ~/Library/InputManagers ~/Library/Mail/Bundles
Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder. You can easily locate any of the folders referred to in this post by copying the folder path here, doing Go > Go to Folder in the Finder, and pasting the folder path there.