I have no idea why it would suddenly change (if you did not touch the settings, it was probably corruption, but I have no idea why). I certainly recommend that here - re-enter the server name. The solution there is to check the server name. Error code 3260' when using MSN account - but it is for incoming. Error code 3259' or 'Could not connect to server check your account settings. If the account is MSN, microsoft has this: Outlook for Mac 2011: 'An operation on the server timed out. Bing certainly doesn't have much on this at all.
We do more Windows Outlook than Mac so i don't know a lot of mac stuff offthe top of my head. Sorry about that - I didn't get a chance to check on this yesterday.
