I am running Exchange server 2013 behing a Forefront TMG 2010 proxy and I am getting the folowing error when running the Exchange connectivity test for ActiveSync.
An ActiveSync session is being attempted with the server.
Errors were encountered while testing the Exchange ActiveSync session.
Attempting to send the OPTIONS command to the server.
Testing of the OPTIONS command failed. For more information, see Additional Details.
An HTTP 403 forbidden response was received. The response appears to have come from Unknown. Body of the response:
Date: Mon, 23 Sep 2013 13:29:41 GMT
Mobile use is enabled and non-provisionable devises are allowed.