I have no idea with this and have been tearing my hair out for ages trying to get mail.app to work with my .mac account, I have had a .Mac account and used mail happily for years, for some reason recently the .Mac account in mail on my MBP has gone offline and refuses to go back online. I have exactly the same settings on my Mac Pro at home and Mail.app works fine there, the .Mac account is fine and I can get mail online and through my iPhone. I have tried changing settings and port numbers, enabling and disabling ssl, I have deleted the account and recreated it in mail, removed the files from my system etc. I really have no idea why it is refusing to work on my MBP. Has anyone else had this problem with their account going offline in the mail.app and what can be done to restore it. I have searched online and through apples support pages but cannot find anything that helps me resolve this.