I have set up a new MacBook Air with Outlook 2011 and have defined 4 different accounts - one on MSN and three POP3 accounts.  Outlook will only send-receive on the MSN account.  One of the POP3 accounts is defined as the default, and I can send just fine using that account, so it is connecting to that server OK.  Contact categories are also behaving strangely, but that's another issue perhaps for another thread.  I'm tempted to uninstall / reinstall Office, reimport the old .pst file and start over defining the POP3 account (the main one) first.