Since last night, my principal laptop (an 11" MB Air running Lion) has refused to send any mail through MobileMe. Incoming mail is unaffected, and mail will cheerfully send from my back-up laptop, webmail, iPad and iPhone, so it's a machine rather than MobileMe issue. Account settings are identical to my other machine, except that the outgoing mail server shows as "MobileMe (MobileMe, Offline)" instead of just "MobileMe (MobileMe)". Connection Doctor shows a successful connection to the outgoing mail server, but sent mail just sits in the outbox and won't go. Any bright ideas? Presumably some kind of settings or authentication issue, but I can't work out what it is.