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gleekFlag for United States of America asked on

Unable to Send Mail from Exchange 2003 to Exchange 2010

I am setting up co-existence between Exchange 2003 and Exchange 2010.


Exchange 2003 is still where are mail comes in and out for the org.  I have configured Exchange 2010 to send mail correctly to Exchange 2003 and then out to the internet using a SEND connector that specifies a 2003 box as the remote host.

The issue is that no one on Exchange 2003 can send email over to Exchange 2010.  The users on the 2003 server send an email, and then it is stuck in the Queue message with an unreachable destination" with state "ready".  

So far i have:

Verified none of the SMTP Virtual Servers for 2003 are pointing to a smart host and all have basic, anon and Integrated Windows Authenticated checked.

I deleted the Routing Group Connector that was installed via the Exchange 2010 install and created a new bidirectional routing group using EMS on the 2010 box.  I have verified it is there both ways and can see it under both Admin groups in Exchange.  I have performed an IIS reset on the Exchange 2003 boxes as I saw in a different article that closely matched mine.

NDR recieved:

This message was rejected due to the current administrative policy by the destination server.  Please retry at a later time.  If that fails, contact your system administrator.

 Telnet from the 2003 to the 2010 server works and mail is delivered.

Not sure as to what I could be missing as I have never encountered this issue after a number of 2010 deployments.


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8/22/2022 - Mon
Antonio Vargas

"Exchange 2003 is still where are mail comes in and out for the org.  I have configured Exchange 2010 to send mail correctly to Exchange 2003 and then out to the internet using a SEND connector that specifies a 2003 box as the remote host."

you do not need to create one send connector on 2010 to send to 2003 box. if they are on the same org 2010 will use send connector on 2003 to send out the org and will use routing group connector created to send to 2003.

start by deleting 2010 send connector and test again. you should stay for now only with 2003 send connector.

Antonio Vargas

test mailflow between 2003 and 2010 only with 2003 send connector (the original).

as the others said you only need one send connector (2003)
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William Peck


Couple of things to check.

1. Do you have a BES in your exchange organization?  

2. Delete & Recreate the routing group connector between the Exchange 2003 and Exchange 2010 Servers.

3. Ensure that Anonymous is enabled in the permission groups of your default receive connector on exchange 2010.


@Vargas - I have removed it and there was no change.,

1. BES - yes.  No users are on

2. I have done this a few times

3. this is set correctly.


1. Run the Exchange pre-deployment analyzer and see if it gives you an error on your Exchange 2003 server regarding permission inheritance.  This is a setting that the BES changes. If it does you need to resolve the issue and restart the mail store.  Let me see if i can find the KB article on it.

2. Ok, just a thought.

3. Great.

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Antonio Vargas

This is for sure a permission problem on exchange 2003.
he wont use the default receive connector on 2010 to communicate so no need to worry about that. focus on routing group connector.
you've said that you can telnet on port 25 between them, but, can you send mail trough the telnet connection? from one 2003 to a 2010 mailbox or vice versa (to be internal). try and check the error to post it here.

I can.

I too believe this is a permissions issue and am working to find out what it is exactly.  I used winroute to browse the 2003 objects and find some things odd in there and am going to verify the computer objects themselves to see if something is incorrect.
Antonio Vargas

Yes, check the permissions on 2003, for sure the issues are on the 2003 box that has the routing group connector to 2010.
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