When I’m traveling and trying to send emails from outlook 2011 for Mac, I get the error message “Not Authorized” and the emails stay in the outbox. (Sometimes if I use a dongle I get the error message “Authentication failed because Outlook doesn’t support any of the available authentication methods”).

After several sending attempts, the emails finally will be sent. This does not however happen every time I send an email, sometimes the emails go through without any problem at all, and sometimes they get stucked in the outbox for a shorter or longer time. The problem also seems to appear only with certain operators, while there is no problem at all with other operators!

All settings for my outgoing server etc are correct according to my own operator, so the emails should be delivered without problems, independently of where in the world I am, or which operator I use.

I also have the latest versions of Mac OS X and Oulook 2011 for Mac.

Any idea of what could cause this strange problem?