We have just finished migrated all of our users from Exchange 2003 to Exchange 2010. We have three sites, each with a 2008 R2 DC, propagating from our corporate site, where the Exchange server is.
After we finished the migration I had a consultant come in and decommission the Exchange 2003 server. Since that has happened, I have several users in the two sites not in our corporate office that now cannot log onto their e-mail. When they do try, or when you try to create a new Outlook profile on one of their machines, Outlook starts popping up a logon screen looking for credentials to log onto the mail server. No matter what credentials you enter or how many times, it just keeps popping up.
Each site has it's own IP scheme, and two of the sites are connected to the corporate site by a managed VPN service. I can ping the email server by name from the client machine, I can also do an NSLookup.
If I try to do a ping or NSLookup from the domain controller in that remote site, it uses the IPv6 address of APPMAIL first and the ping fails, while the NSLOOKUP shows the IPv6 address then then the IPv4 address. I added the IPv4 address for the mail server to the LMHOSTS file and now you can ping from the DC, but NSLOOKUP still shows IPV6 address first.
IPv6 is not enabled on the W2008 DC in the remote site.
I'm at a loss, and I'm not hearing back from my consultant at the moment.