AREXX fake

[Piru]

You don't want to run such script.

The problem is that the faking is too easy to spot. It's trivial to tell that the reply was sent from real address or if it was real "user unknown" reply the mail server.

From this a competent spammer will know that there is a real recipiant at the other end. The only effective way to not get more spam is to delete the spam without any response (can be automated with for example spamassassin).

Responding with "user unknown" will only work if rigged at receiving mail server (that would send such messages normally, too).

[Piru]

I thought that using this mail responce as a template and exchanging string variables (as the date, the sender's domain/address etc.) might do the work.

The idea is good (well if you ignore the fact that it generates even more useless&expensive traffic), but normal user can't do it. You need to control the mail server to generate authentic responses. If you run your own, you can do this, of course.