Can't send Internal Email from Exchange 2010 to 2003 - External Works

We are in the process of migrating from Exchange 2003 to 2010.  The 2010 box has been up and running properly for a few weeks with several mailboxes.  After a server reboot of the 2010 box I can now no longer send internal emails from the 2010 to 2003.  All external emailsfrom the 2010 are being sent and recieved without any issues.  2003 users can also successfully send to the 2010 users.

I have read through some of the other posts but so far I am not having any success and am stuck.  I would appreciate any suggestions.
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matthewataylor1Author Commented:
Another possible piece of information, some of the 2003 users are being prompted for login credentials when opening Outlook.  They can successfully get it is out of the ordinary to be prompted.
Rick FeeMessaging Engineer - Disaster Recovery EngineerCommented:
Sounds like a security rights issue...first run Exchange BPA and if you find any security rights notice issues fix them and it should resolve your issue.

Other idea is delete the existing routing group connectors and recreate:

New-RoutingGroupConnector -Name "Interop Exchange 2003" -SourceTransportServers "exchange2003.localdomain.local" -TargetTransportServers "exchange2010.localdomain.local" -Cost 1 -Bidirectional $true -PublicFolderReferralsEnabled $true

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matthewataylor1Author Commented:
Would I be running the BPA on the 2010 box?
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Rick FeeMessaging Engineer - Disaster Recovery EngineerCommented:
Yes run that on the Exchange 2010 box and include the 2003 server in the BPA health report.    
matthewataylor1Author Commented:
I am needing to intall the .net framework first, then I can run it.  While this is happening, any ideas what security permissions could have/would have changed?  It seems like the 03 box is blocking it.  
Rick FeeMessaging Engineer - Disaster Recovery EngineerCommented:
I have seen people change the default permissions within the Exchange 2003 ESM and it screw up mail flow.   Other odd thing I have seen is everything is fine and have removed the existing routing connectors and recreated and that fixed the issue.
matthewataylor1Author Commented:
I ran the BPA and it did find that the Exchange Domain Servers need to have the allow inheritable checked.  I did that but so far no movement from the mail in the Queue.  Do I need to reboot boxes servers?  I already restarted the Information Store service on both.
matthewataylor1Author Commented:
The messages are still stuck in the queue.  On the 2003 side there is a routing group connector between the two servers.  On the 2010 side I only see one send connector that specifies external traffic.  Should there be one listed for internal use or is that all handled on the 2003 side?
Rick FeeMessaging Engineer - Disaster Recovery EngineerCommented:
so if you run get-routinggroupconnector you only get one one entry...if so this is your issue...i would run remove-routinggroupconnector and in my previous entry follow the example of recreating new  connector
matthewataylor1Author Commented:
After running the get-routingroupconnector it actually shows that I have three.  It sounds like maybe I am best off running the remove command and setting up a new connector.  I am a little leary that I am going to hose up my external sending since that is at least currently working.
matthewataylor1Author Commented:
Also if I remove the current connector will it just delete all the messages currently in the queue?
Rick FeeMessaging Engineer - Disaster Recovery EngineerCommented:
No it will not deleted the messages in the queue.    Also Routing Group connectors are only for inner org communication between Exchange 2003 and 2010 and will not mess up your external sending.    Yes it sounds like you didn't remove the orginal routing group connector.    You can run get-routinggroupconnector to see what you have then delete them all and recreate.
Once you have this all done restart the Exchange routing engine service or wait about about 20 minutes
matthewataylor1Author Commented:
I removed and recreated the routing group connector but the messages are not going out.  In the queue it says that the Primary Target IP Address Responded 535 5.7.3 Authentication Unsuccessful.
On your Exchange 2003 server can you check the properties of the SMTP virtual server?  Under the "Access" tab and then "Authentication" is "Integrated Windows Authentication" checked?

Have you uncheck the "require secure channel" option on the same 2003 SMTP server properties ?

Have you created A records in your internal DNS records ?

Can you add the internal IP address of your exchange 2003 server and the FQDN onto the exchange servers 2010 hosts file ?

matthewataylor1Author Commented:
I am still awarding some points since your answer was very direct and you were so responsive.  Thank you for your help.  The solution offered did not fully resolve the issue and I ended up having to call Microsoft.
Rick FeeMessaging Engineer - Disaster Recovery EngineerCommented:
Thanks for the points!
Can you add the solution that you received from Microsoft to solve this issue?
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