We've recently made a change to the Internal URLs of many of our Exchange Virtual Directories. Following that change, we're seeing end-users report errors from Outlook stating that the certificate cannot be verified because it is expired.
The kicker is that the certificate showing up in these errors no-longer exists on the server. It was removed using the Remove-ExchangeCertificate Cmdlet in the Exchange Management Shell. I've also verified that it no-longer exists in the certificate store at cert:\LocalMachine\My, nor is it visible in any IIS configuration. Additionally, browsing to OWA returns the correct certificate. I don't understand how the server could possibly be serving this certificate any longer.
Is there anywhere else that this certificate could be hiding? Perhaps there is some kind of cache involved with Outlook? Any insight would be appreciated.