RDNS_NONE hits when it shouldn't

gojensen mailscanner at gojensen.no
Wed Oct 21 08:05:47 UTC 2015


We sometimes have issues with mail being flagged because of the 
RDNS_NONE (Delivered to internal network by a host with no rDNS).

In essence this means that the senders IP address has no correct DNS 
setup. However, when we try do nslookup on the mailscanner machine with 
those IP addresses they resolve just fine.

I.e. it seems to be mailscanner or it's part that can't do the lookup 
properly? It was my understanding that mailscanner just used the parts 
of the OS to do this so I'm a bit confused as to why this is an issue.

We're running 4.85.2 on Ubuntu 14.04.2 LTS with local dns caching 
(dnsmasq) with "forwards" to our ISPs DNS and Google DNS, and as I said 
- checking those IPs locally from the shell works just fine. And yes 
nslookup uses localhost as it's server.

// gojensen

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