This problem is related to migration Exchange 2003 to Exchange 2010. User mailboxes on Exchange 2010 are receiving bounce backs for valid users. The bounce backs are similar to fallowing.
|Delivery has failed to these recipients or groups:|
There's a problem with the recipient's mailbox. Please try resending this message. If the problem continues, please contact your helpdesk.
#< #5.2.1> #SMTP#
Possible Cause legacy RGC ( routing group connector) which was created on the installing fist Exchange 2010 server into existing Exchange 2003 org.
Delete the existing routing connector and create new one with PS, note there is no option to create the connector via GUI, deleting can be done from GUI or easily from PowerShell.
See the existing connector open Exchange system manager on exchange 2003 server, or use fallowing PS
|RoutingGroupConnector | FL|
Remove connector you wish
Create RGC from PS for single server
|New-RoutingGroupConnector -Name "Legacy RGC" -SourceTransportServers "Ex1.smtp25.org" -TargetTransportServers "EFE.smtp25.org",-Cost 10 -Bidirectional $true -PublicFolderReferralsEnabled $true|
Create RGC from PS for multiple servers
|New-RoutingGroupConnector -Name "Legacy RGC" -SourceTransportServers "Ex1.smtp25.org","Ex2.smtp25.org" -TargetTransportServers "EFE.smtp25.org","EBE.smtp25.org" -Cost 10 -Bidirectional $true -PublicFolderReferralsEnabled $true|
Oz Casey, Dedeal