I'm tring a solution for a problem that I not sure if the solution
is about PHP or Apache or Linux or something else

I have a little PHP script that mail to anyone.

It is working fine.

But if the destination addr has a problem, I do not receive a reply
from the destination server.

This reply arrives at the ISP and I don't receive any kind of notification.

The web server is an Apache/1.3.9 Server running at a Linux system and the PHP is Version 3.0.12

Any help on this problem would be greatly appreciated.

Rui Torres