Remove preference files and troubleshoot accounts If the first two fixes do not address the problem, users can try removing the Mail application preferences, called com.apple.Mail.plist and located in the ~/Library/Preferences/ folder. Doing this will require mail account information to be reentered, but all previous messages and mailbox setups will remain and be visible again after account information has been supplied. In addition, Mail setup can be compared against that for a fresh account by creating a new user account and logging into that one. Then users can set up Mail and see if the problem persists. If it does not, then users know the problem has to do with their account and can troubleshoot the problem, targeting items in the ~/Library/Mail/ folder, or removing the contents of the ~/Library/Caches/Mail/ folder.