I have recently installed a new Exchange Server 2013 and moved all mailboxes over to it. The old server has been takenout of service and removed from the domain. Before it was turned off was its certificate expired. On the new server appears at each log in a notification about the old certificate on the old server. How do I remove that notification?

Did you uninstall Exchange from the server before taking it out of service? If not, then you have given yourself a pile of work to do because you should always remove Exchange before taking the machine out of service.

Basically Exchange thinks it is still there, so you will have to recover it to remove it correctly.

Simon.

Yes I uninstalled Exchange before removing the server.

Hi,

Please run below command to check the Exchange certificate:
Get-ExchangeCertificate | FL Identity,*not*,Services,Subject,*Domain*

If remain contain the FQDN of old server or it's expired, we will need re-create this certificate. For your reference:
https://technet.microsoft.com/en-us/library/ee332322(v=exchg.141).aspx

Note: After you generate a certificate request, you must submit it to a certification authority, obtain a signed certificate and install the certificate on the same server.

Aften running the powershell there is no mentioning of the old server.

When I began to use the new server I made a new certificate to it. I never renewed the certificate to the old server.