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Troubleshooting Question

Warning Message Outlook after changing certificat

Laurent Pairoux
Last Modified: 2021-03-22

I am having a problem after changing the certificate on my Exchange server. I used to work with a self-signed certificate and installed a certificate from a certification authority.
My certificate is valid for all * .domain.com
My internal domain is mydomain.local

I figured out that in Exchange so I had to change all the links in the virtual directories to direct them to mail.domain.com
I also did an IISreset and the "recycle" option on MSExchangeAutodiscoverAppPool.

I also added in my internal DNS, a domain.com DNS zone with 2 A records:
mail.domain.com to the exchange
autodiscover.domain.com to the exchange

Despite this I still receive on some computers a security alert message because the name of the certificate does not match the name of the server. In the alert, I see that it always takes the local domain name of the server (exchange.mydomain.local).

I therefore meet 2 cases:
- Outlook opens and the message is displayed once, we accept the error and then the message never comes back.
- The message is displayed each time you open Outlook.

If I add on a computer that has only had the message once, the Exchange account of a user who has the message on their computer all the time, I don't even get the security alert message.

I don't understand why users are still going to look for the local domain name to connect to the Exchange.

Do you have any idea where this might come from?

thank you,
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