The final solution: Deleting Mail.app entirely
Tuesday, May 2nd, 2006
A poster on the macOSXHints forum wants to know 
how he can delete all the account information, emails and files that Mail.app uses, so that he can use Thunderbird in peace without wasting disk space.
He is told that he needs to delete the ~/Library/Mail folder. That’s the biggest disk hog, but it is not the only one.
In 10.4.x, Mail.app also sometimes stores attachments in a folder called (by default) ~/Library/Mail Downloads. You could kill that to save some space.
If you are in the mood, why not carry on and delete the Preferences file (com.apple.mail.plist) which stores all your account settings and so on. It’s in your ~/Library/Preferences folder.
For the final purge, you could delete Mail.app itself (46.8 MB) from the Applications folder. A desperately sad business.
Tags: Apple Mail, attachments, deleting, Mail folder, mail.app, Preferences