I have been reading solutions to this problem for a week now and I'm still not able to figure out this certifciate stuff. My migration from WinServer2K3/Exchange2007 to WinServer2K8/Exchange 2010 had been going well until this error started popping up for every user who I moved a mailbox from old to new server.
I understand that I need a CA and I've installed it on one of my DCs. I just don't understand the details of the connection between between the CA and the Exchange Server.
I see that my Exchange server has a default unsigned certificate and I can see the new certificate I can create on my Exchange server, but I don't get how the CA trusts this new certificate and I don't see how my workstation will trust it. Nor do I understand how to get it into my trusted store.
OWA works like a champ, this cert error only shows up when I try to connect with my 2007 clients to the Exchange 2010 server.
Thanks in advance.