In a previous article, we installed Let's Encrypt in Exchange Server. Everything is working great…
Users are getting a certificate warning in Outlook. It happens during or after a new Exchange Server installation in the organization. Why are users getting a certificate warning in Outlook? Is there a way to prevent the certificate warning for the users in Outlook? In this article, you will get both questions answered.
Table of contents
Why are users getting a certificate warning in Outlook?
The reason for this is Outlook and the Service Connection Point (SCP) in Active Directory. During the Exchange Server setup, a new SCP is created in Active Directory (AD). An Outlook client will accidentally discover the unconfigured SCP. It will try to connect to the new Exchange Server instead of the Autodiscover FQDN. Because of that, a certificate warning is showing up in Outlook.
In our example, we did install Exchange Server on a second Windows Server with the hostname EX02-2016 in the domain exoip.local.
Fix certificate warning in Outlook
To fix the certificate warning in Outlook, go through the below steps:
- Find autodiscover URL in Exchange with PowerShell
- Configure autodiscover URL in Exchange with PowerShell
From this moment on, an Outlook client can safely discover this SCP record. Outlook will automatically connect to the correct Autodiscover URL, and therefore, the SSL Certificate warning will not appear (assuming the original Exchange Servers are configured correctly).
In this article, you learned why a certificate warning is showing up in Outlook. It happens during or after a new Exchange Server installation. The next time you install an Exchange Server, you can prevent the certificate warning from popping up in Outlook by configuring the autodiscover URL immediately after installation.
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