I currently have one Exchange Server 2003 in my Windows Server 2003 domain. I have installed a fresh Windows Server 2003 R2 x64 and installed Exchange Server 2007 RTM and pointed it to the bridgehead server. Exchange has installed fine, but I am now getting the following errors in the eventlog. Microsoft Exchange cannot find target bridgehead server CN=SERVER3,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com for routing group connector CN=SERVER9-SERVER3,CN=Connections,CN=Exchange Routing Group (DWBGZMFD01QNBJR),CN=Routing Groups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com in routing tables with timestamp 04/01/2007 13:56:18. Microsoft Exchange is ignoring the target bridgehead server. No target bridgehead servers were found for routing group connector CN=SERVER9-SERVER3,CN=Connections,CN=Exchange Routing Group (DWBGZMFD01QNBJR),CN=Routing Groups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com in routing tables with timestamp 04/01/2007 13:56:18. Ignoring the routing group connector. Microsoft Exchange cannot find the route to mailbox database CN=Public Folder Store (SERVER3),CN=First Storage Group,CN=InformationStore,CN=SERVER3,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com for public folder hierarchy CN=Public Folders,CN=Folder Hierarchies,CN=First Administrative Group,CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com in routing tables with timestamp 04/01/2007 13:56:18. Microsoft Exchange cannot find a route to the source transport server or home MTA server CN=SERVER3,CN=Servers,CN=First Administrative Group,CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com for connector CN=Internet Mail SMTP Connector (SERVER3),CN=Connections,CN=First Routing Group,CN=Routing Groups,CN=First Administrative Group,CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com in routing tables with timestamp 04/01/2007 13:56:18. Microsoft Exchange is ignoring the source transport server. The Active Directory topology service could not discover any route to connector CN=Internet Mail SMTP Connector (SERVER3),CN=Connections,CN=First Routing Group,CN=Routing Groups,CN=First Administrative Group,CN=Administrative Groups,CN=Software Limited,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=soft,DC=com in the routing tables with the timestamp 04/01/2007 13:56:18. This connector will not be used. These errors consistently reoccur, and I have no idea how to fix. Any ideas?

Fixed this too. In Exchange Server 2003 ESM, right click the Exchange 2003 Server and ensure that the 2007 has full permissions.

got the same error! The EX 2007 has full permissions on the EX2003 any other solution?

The above fixed it for me. Have you tried rebooting all your GC servers?

This Fixed it for me too. Thank you