I've had imail running perfectly for years. running most current version of Snow leopard. I have 3 mailboxes, 1 for mobileme, and 2 for comcast. For some reason I highlighted 'Inbox" instead of the individual mail boxes, and ever since then, all my MOBILEME emails are showing up twice, and if I delte one, they both disappear. This is not affecting either of the comcast mailboxes, nor is it affecting my iphone,ipad, or mobileme via Safari. I've quit mail, I've rebuilt the mailbox, and I've restarted the macbook air. Nothing seems to work. Any suggestions would be greatly appreciated!
That's an IMAP account, right? If it is IMAP, and only if it is an IMAP account, try deleting the account from Mail Preferences then recreating it (all your received mail messages will remain safely stored on the IMAP server even though you delete the account from Mail Prefs).