I set up Outlook 2011 in corporate environment. It was working for a few days, sending and receiving mail. Now mail receives fine still, but won't be sent and remains in the outbox. I put those messages in the Drafts folder, open up Mac Mail, and then individually send those messages. I removed the Outlook identity, recreated it, and it was working fine again. Now it's the second day since I did that, and again "A message could not be sent." So I'm back in the loop, believing if I recreated the identity a third time, it will work fine again - for a few days. Any ideas?