Hi,
I have a synology server which is having trouble sending out emails, i have traced the problem to that i haven't setup reverse dos lookup. Unfortunately i don't know how to do this, i have set up a PTR record for one of my domain names but this doesn't seem to work.

Thanks

Simon

PTR record for an IP address maps an IP address to a hostname. It requires that you have a static IP address and have your ISP setup the PTR record.