Good afternoon, we've got a few clients having trouble sending mail through our relay server (postfix on ubuntu 10.04) the error message is blah.server.com verification failed: Name or service not known when I do a lookup on the domain name, it doesn't resolve to an IP and I presume that's why postfix is rejecting it. However, this server authenticates by sender IP or username, it shouldn't care wether or not the sending servers domain name resolves to an IP. I can set this option disable_dns_lookups = yes but it's not clear whether or not this has an effect on the outbound mail, can anyone clarify this?
