I'm in the process of upgrading an Exchange 2003 server to Exchange 2010, and have installed the prerequisites and Exchange 2010 on the new hardware I've purchased.

We use postfix on the perimeter to handle external SMTP connections, and Exchange 2003 is configured to send all external mail via the same postfix instance.

The Exchange 2010 server is now up and running, and I've just performed a mailbox move for a test account to the new server. The mailbox move was flawless, with the client picking up the new server without any problem.

I've then sent an email from the test account (now on Ex 2010) to my own mailbox (still on Ex 2003), which worked fine, but when I reply to the test account, our Exchange 2003 server is attempting to route the message via our postfix instance, instead of routing it to the new Exchange 2010 server.

What might I be missing?

For info, the Exchange 2010 server is installed with the 'typical' roles, as it will be a single server (I intend to keep postfix on the perimeter).

Edit - Output from Get-RoutingGroupConnector executed on the Exchange 2010 server

[PS] C:\Windows\system32>Get-RoutingGroupConnector

Name                      SourceRoutingGroup                             TargetRoutingGroup
----                      ------------------                             ------------------
EX2010-EX2003             Exchange Routing Group (DWBGZMFD01QNBJR)       first routing group
EX2003-EX2010             first routing group                            Exchange Routing Group (DWBGZMFD01QNBJR)

I would run Get-RoutingGroupConnector and verify that you have a connector from your EX03 back to your EX10 environment, and from your EX10 to your EX03. Although, your test seems to indicate that you DO have a connector from your EX10 to your EX03. You may just be missing one from your EX03 to EX10.

IF so you can create a new connector using

New-RoutingGroupConnector -Name ex10-to-ex03 -sourcetransportserver ex03server -targettransportserver ex10server

Add -PublicFolderReferralsEnabled $True to the end of the above command if you need access to Public Folders, across the connector.

  • 1
    I think you've got the connector recommendations backwards. Ex2010 -> Ex2K3 works; So Ex2K3 must be missing the connector (which the Ex2010 install does not setup by default IIRC). – Chris S Sep 9 '11 at 13:54
  • I've checked, (extra info added to question), and I do appear to have both routing group connectors. - aha, looking in ESM on my Exchange 2003 server, I only have one connector showing (EX2010-EX2003) – Bryan Sep 9 '11 at 14:04
  • ESM doesn't let me edit this though, it complains that I need ESM version 8.0.30535.0 or greater to do this. – Bryan Sep 9 '11 at 14:07
  • @Chris S - You are right, I read it backwards, too early in the day for this ha. Updated answer. – HostBits Sep 9 '11 at 14:08
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    @Bryan ESM will only show the 03-to-10 connectors, and you can only edit them with EMS (since they were created when you installed Exchange 2010). Looks like you have to correct connectors in place. could you do a Get-RoutingGroupConnector | FL and verify they are all all showing "isValid : True" and The proper servers in the SourceTransport/ TargetTransport sections. – HostBits Sep 9 '11 at 14:11

Does your Exchange 2010 server have a Receive Connector setup and configured to receive email from your Exchange 2003 server? If not, you need to do that. Create a Receive Connector and specify the IP address for your 2003 server in the network scope.


The SMTP virtual server in the Exchange 2003 routing group was configured with a smarthost. This doesn't appear to be a supported configuration.



I've now configured the Exchange 2010 to handle the sending of external mail with a send connector configured to send via our postfix MTA. I've also reconfigured postfix to deliver mail to the Exchange 2010 server, which is happily able to route to mailboxes still on the Exchange 2003 server.

This was a step I would have had to perform earlier, however I've just ended up doing it a little sooner that I originally planned.

  • That's interesting, For some reason I had thought you were referring to a smarthost configured on an Internet Mail connector in 2003. Makes sense now. – HostBits Sep 9 '11 at 20:48
  • Apologies if I didn't explain myself very well. Appreciate all your help, which did help drive me towards the solution. – Bryan Sep 9 '11 at 21:02

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