Question : How to custom NDR message in Exchange 2007 and disable NDR for internet email sender

Question 1:
In Exchange 2007, the format of NDR is like below, how can I custom it ?

(Sorry, we couldn't deliver your message to the following people or distribution lists. We hope the information below helps you understand what happened. Please read it carefully.
[email protected]
It looks like you might have typed the wrong e-mail address. Please check the address and try again, or ask your system administrator for help.

Sent by Microsoft Exchange Server 2007 )

Question 2:
Can I disable the NDR for the email sender from internet?  I do not want the spammer do email harvesting by trying different email address with the valid domain name.  Subject to the current configuration, if I send an email from Hotmail account to a non-existence email address with the valid domain, I (internet email sender) will receive a NDR from Exchange 2007.  For all inbound email, there should be no NDR.  The NDR is just for our internal user who send outbound email or for internal only.

Answer : How to custom NDR message in Exchange 2007 and disable NDR for internet email sender

You can change your NDRs, what is used to generate them and the message which is sent back to the user by using Transport Rules: http://www.msexchange.org/tutorials/Transport-Rules-Exchange-Server-2007.html. You cannot change the default text of the message though, only the text associated with the error code.

Don't disable NDRs for Internet email. Doing so is more than likely to get you blacklisted very quickly. NDRs are a requirement for email servers to follow, so switching them off is going to be more of a problem for you than someone doing email harvesting. You might want to look at Recipient Filtering http://technet.microsoft.com/en-us/library/bb123891.aspx and tarpitting instead: http://exchangepedia.com/blog/2007/01/enabled-by-default-smtp-tarpit-in.html. These are much better, approved ways of trying to prevent or slow down a spammer trying to pick off email addresses in your domain, one by one.

-tigermatt