We attempted to place our exchange 2010 server into production (coexistence with exchange 2003) but had to back out as mail would not flow from exchange 2010 to exchange 2003 or from the Internet to 2003. Mail from 2010 mailbox and 2003 mailbox to the internet worked and mail from the internet to 2010 mailbox worked. Essentially, mail destined for the 2003 server would get stuck in a loop on 2010. The queue stated a local loop was detected. I think it may be related to how we are trying to implement exchange 2010.
Our environment is currently 1 Exchange 2003 server FE/BE. We are attempting to transition to 1 Exchange 2010 server with MB/CAS/HUB roles.
Here is where the problem lies.
Current exchange 2003 FQDN is exchange.domain.com
Current exchange 2003 DNS name is exchange.domain.com
We want to keep the DNS name exchange.domain.com for our OWA users.
So when we try to implement 2010,
Exchange 2003 FQDN is exchange.domain.com
Exchange 2003 DNS name becomes legacy.domain.com
Exchange 2010 FQDN is exchange2010.domain.com
Exchange 2010 DNS name becomes exchange.domain.com
I think this is what is causing mail to loop in exchange 2010 as the netbios name of exchange 2003 is “exchange” and the DNS name for exchange 2010 becomes “exchange.domain.com”
Can anyone provide some insight as to whether this is even possible or what we may be doing wrong?