This topic describes the steps to troubleshoot the accessibility issues to the ENS server on a cloud ENS installation and on an on-premises ENS installation.

Troubleshooting Accessibility Issues to the ENS Server from a Cloud ENS

Probem: Check if the cloud ENS is accessible from the ENS server and confirm if the ENS server is accessible from the CAS or the Mailbox server.

  1. Access the following URL in a browser on all CAS or mailbox servers:

    https://{ENS cloud URL}/api/ens/alive.

  2. Select the ENS cloud URL based on your region.
    Region ENS Cloud URL
    North America
    Asia Pacific
    European Union (EU)
    United Kingdom


You must receive the following response:

If you are unable to see a similar response, then whitelist the IP addresses and endpoints and validate the connection to the ENS server. To see the supported ENS2 API endpoints, refer the ENS Endpoints and IP Whitelist.

Troubleshooting Accessibility Issues to the ENS Server from an On-Premises Installation

Problem: Check if the ENS server is accessible on an on-premises setup and is receiving the request. After an on-premises ENS installation, confirm that the ENS is installed and running on the ENS server.

  1. Navigate to the following URL in a web browser and check the same server where ENS is installed. The user localhost is mentioned as follows http://localhost/MailNotificationService/api/ens/alive and https://localhost/MailNotificationService/api/ens/alive. To check from outside the ENS server, see http://{ENS server public url}/MailNotificationService/api/ens/alive and https://{ENS server public url/MailNotificationService/api/ens/alive. You must be able to see the following response:
  2. Confirm that a certificate is imported and 443 is bound to the website if you have an issue with the https 443 traffic.


Confirm if the ENS is receiving the request from outside (for example, receiving the request from a browser when you reach the alive endpoint). When verifying the ENS alive endpoint, the IIS logs are generated. The IIS logs are by default stored at the following path: %SystemDrive%\inetpub\logs\LogFiles. If you do not find the logs at the default path, then the logs for your IIS might be stored at a different location. To get the path for the IIS logs, check the following link: Managing IIS Log File Storage.

For other successful ENS traffic, you might see the following log entries in the IIS logs.

Test the Exchange Web Services URL

The Exchange Web Services (EWS) subscriptions notify changes in a users' mailbox. Use the Microsoft's Remote Connectivity Analyzer online tool to test the EWS URL. You can test the EWS URL only if the EWS is configured for the basic authentication and the EWS is publicly available.

  1. Open the Microsoft's Remote Connectivity Analyzer.
  2. Select the Synchronization, Notification, Availability, Automatic Replies under the Microsoft Exchange Web Services Connectivity Tests and click Next.
  3. Enter the Email address, Domain\User Name (or UPN), Password, and Confirm Password information.
  4. Enter the EWS URL manually, if the autodiscovery is not enabled or select the Use Auto-Discovery to detect server settings if autodiscovery is enabled.
  5. Click Verify account and perform the test.


If there are no issues, the following success message appears:

If the connectivity test fails for the following reasons, then expand the error to see more information.

You see the following 401 error when the user is unauthorized.

You see the following error when the autodiscovery is not enabled.

You see the following error when the Remote server cannot be resolved.

Troubleshooting the EWS Accessibility on an On-Premises ENS Installation

Use the EWSEditor tool to check if the EWS is internal and accessible from an on-premises ENS. The EWSEditor tool works only if you are using basic authentication or Open Authorization (OAuth).

  1. Download and extract the EWSEditor ZIP file from the EWSEditor.
  2. Run the EWSEditor.exe file.
  3. Navigate to the File > New Exchange Service and enter the Service URL, User Name, Password, and Domain.
  4. Click OK. If there is an error in the details entered, then an appropriate error message appears. If the details entered are correct, then the following message appears:
  5. Click Yes.
  6. Select the device for which you want to check the subscription and right-click on the device. Select Open Streaming Notifications Viewer.
  7. Click Subscribe and Clear Events.
  8. To test the notifications, send a test message to the device. If the test is successful, the following screen appears: