There are lots of ways to do nearly anything in Exim, but why not use
the simple expansion variable?
deny condition = ${if eq{$host_lookup_failed}{1}}
message = Reverse DNS lookup failed for host $sender_host_address
On 6/7/25 5:23 PM, AC via Exim-users wrote:
>
> I want to block any connection that doesn't have a successful rDNS (logs
> report "no host name found") but searching around results in so many
> different variants of an ACL rule to do this.
>
> What is the proper way (likely in acl_smtp_connect if I'm not mistaken)
> that will simply reject any conection that comes from a bare IP with no
> rDNS? Note I'm not asking that I block something where the incoming
> hostname doesn't match the rDNS where the two might mismatch (such as an
> MX record vs. a more general domain), I'm only looking to block anything
> that has absolutely no rDNS value so I don't want to use the
> "reverse_host_lookup" option.
>
> The closest thing I found was in the mailing list from 2008:
>
> defer
> !condition = ${lookup dnsdb{defer_never,ptr=$sender_host_address}{yes}}
> message = Reverse DNS lookup failed for host $sender_host_address
>
>
>
> Is this still a correct suggestion?
>
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