I have a Microsoft Office 365 account I've been using for about 6 months.  I primarily use my Outlook on my PC rather than from the account on a browser.  Today I tried to start up Outlook and I get an error window:  "Cannot start Microsoft Outlook.  Cannot open the Outlook window.  The set of folders cannot be opened.  Microsoft Exchange is not available.  Either there are network problems or the Exchange service is down for maintenance."  I can still access my 365 account through the browser/cloud.  There is no network problem and the exchange service is not down for maintenance.  I've shut down the computer and restarted it, but keep getting the same message.  Any ideas?

Hi Trock,

Thank you for your question.

One of the possible causes is that we are using Microsoft Office Outlook and disable the Encrypt data between Microsoft Office Outlook and Microsoft Exchange profile setting. The default configuration for Exchange Server 2013 requires RPC Encryption from the Outlook Client, this prevents the client from being able to connect. We could refer to the following link to enable Encrypt data between Microsoft Office Outlook and Microsoft Exchange to check if the issue persist:

https://support.microsoft.com/en-us/kb/3032395

if the issue persist, we could rebuild the profile to check if we could open outlook:

If there are any questions regarding this issue, please be free to let me know.

Best Regard,

Jim