OK, i found the problem, and it is teh following:
3 years ago, the mail acounts was managed by an ISP, and there was 4 acounts that i dont create when mount the sme email server, those acounts are spamed all the time and as the domain is the same, qmail accept the email but when look at the acount does not exist in the server makes double bounce emails.
So rigth now that i konw what happend, i wana know a way to stop this, how can i reject email to some acounts??? or if the rigth solution is other, what it is?
thanks