Test Connection fails from Email Server Profile in Microsoft Dynamics 365

This article provides a solution to an issue where Test Connection fails from Email Server Profile in Microsoft Dynamics 365.

Applies to:   Microsoft Dynamics 365 Customer Engagement Online
Original KB number:   4493267


When using the Test Connection option from an Email Server Profile in Dynamics 365, the test fails and you may see an error like the following example:

"Remote server error: (401) Unauthorized. Make sure the user name and password you entered are correct and try again." or

"System.Net.WebException: The operation has timed out at System.Net.HttpWebRequest.GetResponse()
at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeConnectivityDiscoverer.ValidateServerUrl(EmailDirectionCode emailDirection)"


  • Cause 1: The username or password isn't correct.

  • Cause 2: If you're using Dynamics 365 (online) to connect to Exchange on-premises, this error can occur if your firewall doesn't allow connectivity from Dynamics 365 to your Exchange server.

  • Cause 3: In some cases, the test connection may fail even though the credentials are correct and connectivity isn't a problem. See Resolution 3 in the Resolution section.


  • Resolution 1: Verify the username and password are correct.


    The User Name value needs to be in UPN (User Principal Name) format. Ex. username@contoso.com instead of contoso\username.

  • Resolution 2: If you're using Dynamics 365 (online) with Exchange on-premises, verify your firewall allows connectivity from the list of IP ranges documented in Microsoft Dynamics CRM Online IP Address Ranges including the referenced Azure IP ranges.

  • Resolution 3: The Test Connection results aren't always reliable. If the same username and password works when doing a test connection from Microsoft Remote Connectivity Analyzer, use the Test & Enable Mailboxes option in Dynamics 365 instead of the Test Connection option. If the Test & Enable is successful for your mailboxes, you can disregard the results from the Test Connection dialog.


    If any failures occur using the Test & Enable Mailboxes button, see the Alerts tab within the mailbox record and review any help links that are included.