Environment. 1 Exchange 2007 HUB/mailbox, 1 CAS.When an internal sender sends to an internet address that doesn't exist, the internal sender receives an NDR but no copy goes to the mailbox I created and designated MicrosftExchangeRecipientReplyRecipient. All copies of NDRs sent by internet senders go to this mailbox successfully. I have defined all the codes for NDRs.What am I doing wrong? Do I need to designate the Postmaster mailbox as MicrosftExchangeRecipientReplyRecipient.Thanks

Did you follow:http://msmvps.com/blogs/andersonpatricio/archive/2007/07/24/copying-ndrs-to-a-mailbox-in-exchange-server-2007.aspx

Yes, except I used a mailbox named NDR Copy and mapped it to MicrosftExchangeRecipientReplyRecipient. Should I have used the Postmaster maibox instead?Also, as I stated earlier, messages from internet senders to invalid internal recipients get copied to this mailbox successfully.

Changing the MicrosftExchangeRecipientReplyRecipient to Postmaster had no effect.