451 4.4.0 Primary target IP address responded with: "421 4.4.2 Connection dropped due to SocketError."

I am deploying a Exchange 2010 installation into a 2003 environment with hopes of transferring mailboxes to the new 2010 server. However, I'm having some current issues with testing to get the environment at least coexistent so I can properly move over.

The Exchange 2010 server is using a 2010 Edge Transport as well.

On Wednesday we pointed the MX records at the Edge server and it seemed that mail flow between the 2003 and 2010 servers was good, and flow to and from the Internet was good as well. Then comes this morning where a lot of mail (655 messages now) destined for the 2003 legacy boxes (at this point it was 95% of the organization) were being stuffed in a queue on the 2010 box called SmtpRelayToTiRg. Also no messages between the 2003 server and 2010 server were flowing.

The error message in the title of this thread is the error being displayed on a lot of the messages in that queue.

I followed instructions from here which fixed the 2003 to 2010 flow, but not the 2010 to 2003 flow.
http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/8a15576d-ff5e-43bb-a92a-5dffef547465/

I am now able to send mail from 2003 to 2010. I cannot send mail from 2010 to 2003. Mail flows to and from the Internet to the 2003 boxes. And I can only send mail destined for the Internet from the 2010 boxes. That also caused messages on the 2003 server's queue to be sent to the 2010 mailboxes successfully.

I also am getting this error a few times in the Event log on the 2010 box from MSExchangeTransport:

MSExchangeTransport Event 5020
The topology doesn't contain a route to Exchange 2000 Server or Exchange Server 2003 2003-EXCHANGE.contosophx.contoso.org in Routing Group CN=First Routing Group,CN=Routing Groups,CN=First Administrative Group,CN=Administrative Groups,CN=Contoso Company,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=contosophx,DC=contoso,DC=org in routing tables with the timestamp 9/23/2011 8:42:51 AM.

MSExchangeTransport Event 5006
Cannot find route to Mailbox Server CN=2003-EXCHANGE,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=Contoso Company,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=contosophx,DC=contoso,DC=org for store CN=MailboxStore,CN=Second Storage Group,CN=InformationStore,CN=2003-EXCHANGE,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=Contoso Company,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=contosophx,DC=contoso,DC=org in routing tables with timestamp 9/23/2011 8:42:51 AM. Recipients will not be routed to this store.

At this moment, we've rolled back the MX/A records to the original 2003 server, and moved some of the mailboxes back to the 2003 server as well (only test boxes remain on the 2010 server).



I'm more than happy to provide any information or answer any questions. I apologize I may not get back to any questions for the next few hours.