terminate spamming

[Mauro Tablo']

I run qmail on a linux server and there's a hard spamming through it. In my server there are four domain (three are virtuals). I set the rcpthosts file with the names of my domains (one per row). The problem is that now users of my domains can't send out mails. I know that one possible solution is to set the relayclient file, with ip addresses of my net. But doing so, I don't allow my users to connect from other addresses (for instance, the address given by an internet provider). The best way is to allow relaying only from "mydomain_1", "mydomain_2", etc., but anyone can be validated, if tells to my host he is anyone@mydomain_X, and spamming doesn't stop.