If you read this thread carefully you may see that the answer you are looking for is: yes, it can be done. you can craft the bounce in perl. You can send the NDR via perl. Don't do it, because the MTA is the place for this to happen. Don't do it because spam addresses and relay routes are oft forged and the bounce that you generate will just sit in queue or go to the wrong person. Don't do it because your setup of a wildcard virtual user is silly and eating unnecessary spam attempts at random names. don't do it because there is a better way.

You have to realize that just because those answers are not what you wanted to here they are still answers, sometimes they are the most valuable answers of all because they make you look at the problem from a wider perspective than you were capable of in the first place. Don't discount peoples responses because they are not what you wanted to hear -- they are being given to you from other admins and developers toolbox of previous experiences, that is what makes them so valuable. If you just want yes or no answers to your question without advice or requests for more info, novelty shops sell the famous 8 ball fortune tellers in every town, just keep on shaking it til you get the answer you want.