Exchange ActiveSync Returned an HTTP 503 Error
Topic Last Modified: 2013-03-21
The Exchange Remote Connectivity Analyzer includes the Attempting the FolderSync command on the Exchange ActiveSync session test. This test determines whether the information store on the Microsoft Exchange 2010 server is mounted.
If the information store is dismounted, you receive the following error message:
Exchange ActiveSync returned an HTTP 503 response (Service Unavailable).
For information about how to start the Information Store service, see How to Start the Microsoft Exchange Information Store Service (MSExchangeIS).
For information about how to mount the information store in Exchange 2010 server, see Mount a Database.