qmail behind a firewall

[Jos Okhuijsen]

Hi there,   We run qmail on a box behind a firewall, another, lower priority, external smtp server knows it's way through and can deliver to our machine, bounces however go to the return adress, and double bounce.   The DNS MX priority is 10 for the machine behind the firewall, and 20 for the public machine.   The return address is always behindSmpt.domain.com, both using SMTPserver behind the firewall as well as an SMTPserver in the public.   Questions: Is the return-address always constructed from the MX records in the DNS? Is there a way to fix the returnaddress to point to the beforeFirewall box? (other than fixing the DNS)   Jos