Test Connection fails with 401 or time-out error in email server profile in Microsoft Dynamics 365
This article provides a solution to an issue where Test Connection fails from an email server profile in Microsoft Dynamics 365.
Applies to: Microsoft Dynamics 365
Original KB number: 4493267
Symptoms
When you test connection on an email server profile record in Dynamics 365, the test fails and you might see one of the following errors:
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: Incorrect username or password
To solve this issue, verify the username and password are correct.
Note
The User Name value needs to be in the UPN (User Principal Name) format. For example, use username@contoso.com instead of contoso\username.
Cause 2: Firewall blocking connectivity
If you use Dynamics 365 (online) with Exchange on-premises, ensure your firewall allows connectivity from the list of IP ranges documented in Power Platform URLs and IP address ranges including the referenced Azure IP ranges.
Cause 3: Unreliable test connection results
The test connection results aren't always reliable. If the same username and password works when testing connection with Microsoft Remote Connectivity Analyzer, use the Test & Enable Mailboxes option in Dynamics 365 instead of the Test Connection option. If the Test & Enable Mailboxes is successful for your mailboxes, you can disregard the results from the Test Connection dialog.
Note
If any failures occur using the Test & Enable Mailboxes button, see the Alerts tab in the mailbox record and review any help links that are included.