I set up my email to use IMAP for Outlook.com on Outlook 2011 for Mac. All has been working fine but since yesterday I keep getting the following error whilst trying to check my email

MAIL COULD NOT BE RECEIVED AT THIS TIME

The server for account xxxxxxx returned the error

Error 8: Server Error. Please try again later. Your

username/password or security settings may be

incorrect. Would you like to try re-entering your

password?

I can login to my outlook account on web without a problem.  I only have the problem when trying to retrive mail on my mac on outlook 2011.  What is causing this problem?

Many thanks