Re: [exim] rDNS lookup problem

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Autor: Jasen Betts
Data:  
Dla: exim-users
Temat: Re: [exim] rDNS lookup problem
On 2016-06-10, a.smith@??? <a.smith@???> wrote:
> Hi,
>
>    I'm running Exim 4.86.2 on FreeBSD 9.3 and I'm having an issue  
> whereby it is registered incoming mails as originating from hosts  
> without an rDNS record, but they do have an rDNS record. I've just  
> enabled the X-Host-Lookup-Failed ACL to add the extra header and it  
> confirms what I was seeing by enterpreting the "Recieved:" header.

>
> For example when sending from 93.191.32.251 I see:
>
> X-Host-Lookup-Failed: Reverse DNS lookup failed for 93.191.32.251 (failed)
>
> and
>
> Received: from [93.191.32.251] (port=49828 helo=asigra2.ldex.co.uk)
>
>
>
> but nslookup from the mail server itself provides:
>
> nslookup 93.191.32.251
> Server: 8.8.8.8
> Address: 8.8.8.8#53


Don't use google DNS, if you hammer them they'll start randomly
denying your requests. install your own DNS.

> Any clues as to why Exim is failing when nslookup/dig from the same
> host using the same DNS server work?


could be 8.8.8.8 not suited to production use.

I've been using bind with no fowarders (just root-servers) for two
years and the only times it's given the "wrong" answer is when the
source DNS servers were misconfigured. (on debian linux this is the
default configuration of bind)

--
\_(ツ)_