I am in the process of moving to exchange 2010. I have two domains contoso.com and kontoso.com. On the exchange 2010 hub transport, I have set up two accepted domains contoso.com and kontoso.com set up on the hub transport and the mailnboxes for both contoso.com and kontoso.com set up.
The exchange 2010 points to a dual-brain DNS for contoso.com and kontoso.com initially set up to simplify look up for internal and external IP addresses. The WIndows 2008 R2 AD name is contoso.com and cannot change.
Currently kontoso.com is already moved to exchange 2010 but not contoso.com. What I need to do now is to temporarily point emails intended for contoso.com to another non-Exchange email server on the Internet until the move over to Exchange. After the following attempts I get the "451 4.4.0 Primary tartget IP address responded with "421 4.2.1 Unable to connect." Attempted failover to alternate host," message when attempting to send mail from address from kontoso.com to address to contoso.com:
1. Change the accepted domain contoso.com from authoritative to internal relay.
2. Set up a send connector for internal relay with cost=1, use DNS MX record to route email.
3. Temporarily removed the smtp addresses for mailboxes for contoso.com using EMC.
4. On the AD DNS, set up forward lookup zones MX to point to the existing mail server for relay.
I suspect the problem lies with the AD name and smtp domain name are the same as contoso.com. Since I can't change it, are there any solutions in sight for this problem? This arrangement needs to go online in this week.