When you introduce a the first Exchange Server 2007 server into an existing Exchange Server 2003 organization you may encounter an issue with mail flow between the two servers.
Emails sent from Exchange 2007 to Exchange 2003 work fine, however emails sent from Exchange 2003 to Exchange 2007 do not work and can be seen in the deferred delivery queue of the Exchange 2003 server.
This issue can be caused by the use of a smart host configured on the Default SMTP Virtual Server on the Exchange 2003 server.
To resolve the issue remove the smart host from the Default SMTP Virtual Server and instead configure a new SMTP Connector for the Routing Group to send internet email (the namespace of “*”) to the smart host.
About Paul Cunningham
Thanks alott, I was experieencing this problem after exchange server 2007 installation, I am vegreatfull to you it realy solved my isuue, keep the good work continue
Thanks from an Exchange guy in Victoria. I already suspected it was that but it’s good to get confirmation before I do the configuration changes.
I have this same issue, where Exchange 2003 cannot send to 2007, but I do not have a smarthost. Any thoughts?
DFad, on the Exchange 2007 server run Get-RoutingGroupConnector from the Exchange Management Shell and make sure you have RGC’s going both ways.
Thanks Paul, this posting helped me solve a Ex2003 to Ex2003 delivery problem. We added a second Ex2003 server to our setup last night but couldn’t get the messages flowing between them and out to our smarthost at the same time. Thanks again!
Thank you very much…it workd for me.
Thanks for this tip, solved my problem in an instant!!! Woul;d also point out that this was on a 2003 to 2010 migration, so the tip works for that scenario as well.
Now if all goes well and I can move the mailboxes across overnight, I’ll get a day off in the sun tomorrow! So double thanks!
You are the best, man! I couldn’t migrate because of this issue….can’t thank enough.