On 2/10/2016 2:35 PM, Nick Howitt wrote: >> This particular client has no reverse DNS hostname. Most sites find >> it safe to use reject_unknown_reverse_client_hostname to reject such >> clients. This similar to restrictions at many big mail providers and >> is a much safer alternative than reject_unknown_client_hostname. >> http://www.postfix.org/postconf.5.html#reject_unknown_reverse_client_hostname >> > Unfortunately the thread has split so I asked this question replying > to another post. My concern is do many mailers use IP's with no > reverse DNS records. Presumably if they are dynamic they'll be > picked up by the zen rbl anyway?
This particular client isn't in zen, and probably not dynamic. The reject_unknown_reverse_client_hostname is quite safe. You can try it out for a while with warn_if_reject reject_unknown_reverse_client_hostname somewhere in your config. It's quite rare for a legit mail server to fail this check. The few failures I see are typically when someone moved to a new IP and forgot to set up the rDNS. > > Presumably if I want more I need to change the verbosity. Everything you need is in the normal logs. -- Noel Jones
