Hello,When a message is received that cannot be delivered due to transport rules (such as message size), the server is generating a DNR, however this is never being received by the external sender.Small Business Server 2008, Exchange Server 2007 SP1I have checked the Get-RemoteDomain "Default" | fl *AutoReplyEnabled : FalseAutoForwardEnabled : FalseDeliveryReportEnabled : TrueNDREnabled : True <<<< NDR Is enabledI have tried toggling the setting, and can see the NDR in the Tracking Logs for the message received that it is over limit.550 5.2.3 RESOLVER.RST.SendSizeLimit; message too large for this senderMy question is, how can you determine whether the NDR is leaving the exchange organisation, and is there a setting that I am missing to ensure that it is enabled to allow the NDR to leave the org.Thanks,Paul MacNeill