Have have OS 10.5.8. I am having numerous problems with MAIL. I think it is time to reinstall MAIL. How do I reinstall just MAIL? Also, are there files I need to take out of certain folders so my data does not get lost? Like p.lists and stuff?
Plus write down your email server settings. Then navigate to /YourHardDrive/Users/YourUserName/Library/Preferences/ and find the file com.apple.mail.plist and move to you trash can. This will reset Mail without deleting your saved email. You will just have to re-add your email server accounts again but this will reset Mail. Doing this along with reindex of Mail should fix your problem.