UPDATE:

The security patch update for Exchange 2010 has been completed. Exchange 2013 is still underway. There should be no more repeated authentication prompts from Outlook clients and there is no expectation that the issue should repeat during the rest of the maintenance cycle.

If you have any additional questions please reach out to our support team. We will provide an update when the Exchange 2013 maintenance is complete.

ORIGINAL POST:

The security patch update for Exchange 2010 & 2013 is currently still underway. During this time, users may experience repeated authentication prompts when accessing email via Outlook Clients 2013 and 2010. Email can still be checked via Outlook Web Access while the patch continues at https://na02.msexchangeoutlook.com

Our Engineering team is working on resolving this issue while the patch completes. If you have any questions, please do not hesitate to reach out to our support team.