Mail app crashes-doesn't finish downloads from server

Question

Mail app just started crashing this morning. It will start downloading from the server, then crashes. Ran fine yesterday.
Things I tried. Restarted computer, Ran Applejack no issues. Created a new user. Mail works there. I'm guessing one of the preferences is corrupt. But which one?
everything up-to-date

Answer 1

You’re welcome, but disabling the junk filter was meant just to identify the problem; it’s clearly not an acceptable solution. If the junk filter is crashing on you, try resetting the junk filter database (Preferences > Junk Mail > Reset) and re-enabling the junk filter. If Mail starts crashing again, proceed as follows to thoroughly get rid of all the files used by the junk filter, so that Mail creates them anew:
1. If you have a .Mac account and .Mac synchronization of Mail data is enabled either in Mail > Preferences > General or in System Preferences > .Mac, disable it before proceeding.
2. Quit Mail if it’s running.
3. In the Finder, go to ~/Library/Mail/.
4. Locate LSMMap2 and move it to the Trash. This file stores information about what does and doesn’t constitute junk, and allows the junk filter to learn. Deleting this file is what Preferences > Junk Mail > Reset does. The file was called LSMMap in early versions of Mail; delete that as well if you see it.
5. Locate any MessageRules.plist (Mail 2.x) and/or MessageSorting.plist (Mail 1.x) files and move them to the Desktop. This is where Mail stores all the rules, including the rule that governs what the junk filter does.
6. Locate DefaultCounts and move it to the Trash. This file keeps statistics about the number of messages that have been marked as junk, either automatically by the junk filter or manually by the user.
7. Look for the account folders. The name of each account folder starts with the account type (POP, IMAP, Mac), followed by the account username and the incoming mail server. Open each of the account folders, locate the Junk.mbox or Junk.imapmbox folder within it, and move it to the Trash if present.
8. Go to ~/Library/Mail/Mailboxes/. Locate any Junk.mbox mailboxes there (their name may include the account name in parenthesis), and move them to the Trash.
Note: Steps 7 and 8 may be unnecessary. Also, messages in Junk mailboxes with an .mbox suffix are stored locally and will be lost forever as a result of doing steps 7 and 8. If there is a chance that you have legit messages there that you want to preserve, either try skipping those steps, or move the messages to another mailbox in Mail first, or move Junk.mbox to the Desktop (to be imported back later) instead of to the Trash. Junk mailboxes with an .imapmbox suffix aren’t a concern because they are stored on the server and Mail would rebuild them automatically.
9. Open Mail. As a result of removing the rules file, the junk filter will be disabled now. You may want to either shut down the Internet connection before opening Mail or take Mail offline immediately after opening it, to prevent Mail from downloading anything until the junk mail filter has been enabled again.
10. Go to Mail > Preferences > Junk Mail and enable the junk filter.
11. Go online again if you went offline in step 9.
12. If the problem is fixed now and .Mac synchronization of Mail data was enabled at the beginning, enable it again, go to System Preferences > .Mac > Advanced, click Reset Sync Data, and choose the appropriate options to reset the Mail data stored on the .Mac server with the data locally stored on the computer, i.e. sync data must flow from the computer to the .Mac server.
If the above solves the problem and you don’t have any rules you’d like to preserve or recreating them is not a daunting task, the files moved to the Desktop in step 5 can be deleted.
Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder. That is, ~/Library is the Library folder within the user’s home folder, i.e. /Users/username/Library.