Odd issue, which I believe to know why it's happening, but not how to fix it right now.
We recently acquired a new company, they are using Outlook 365 and still connecting to and using their old email domain, not connected to our Exchange servers at all. However, they do log on to our domain.
We are putting up a new Exchange 2010 VM and transferring mailboxes for the rest of the company over.
Only these users not configured for our email are getting a security warning for the new exchange server:
server.domain.local - information you exchange with this site cannot be viewed or changed by others. However, there is a problem with the site's security certificate.
With the name on the security certificate is invalid or does not match the name of the site being the one marked with the red X.
So I believe since they log onto our domain, for some reason Outlook autodiscover is seeing the new server even though it's not even configured to use it for email... how can I prevent this error?
The old exchange server never gave errors, and is still running. I do not have any services pointed and running on the new server yet. I do have a UCC certificate installed on the new server, the old one only had a self signed certificate, but as mentioned, never gave any errors to them.