is it possible to create a custom bounce back message from exchange 2003?

Anything is possible. I don't think what you want is feasible.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

In Exchange 2003, I'm afraid it is not possible. Similar post, please see: Customizing NDR in Exchange 2000/2003 http://social.technet.microsoft.com/forums/en-US/exchangesvrsecuremessaging/thread/39ed92f0-02dc-4baf-b790-7ef5d54c04cf/ Modify NDR notification message, is possible? http://social.technet.microsoft.com/Forums/en-US/exchangesvrdeploy/thread/0ca808eb-a7be-4a89-837c-c5fe94eadd12/Frank Wang TechNet Community Support

My answer is more accurate. It is possible, but you have to write your own Exchange DLL.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."