Originally Posted by Debianer
PTR record must be created by my ISP?
My hostname is vectranet.pl, but my domain is different, so revDNS for my IP do not point to my mail domain.
The PTR must point to a domain/hostname that in return points back to the same IP. It doesn't matter if it's your hostname or something like dgbg123523452.rthrt435634.yourisp.com.