Re: [exim] Failed reverse_host_lookup

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Author: Marc Sherman
Date:  
To: exim-users
Subject: Re: [exim] Failed reverse_host_lookup
Sam wrote:
>
> I'm a little newbie with exim and don't see exactly where to search to
> tell my acl to consider failed reverse dns as if there were no reverse
> dns at all ... beacause I think that's the problem in the error log.


Did you bother to grep the Debian default config files for
reverse_host_lookup? If you had, you would have found:

>   # Warn if the sender host does not have valid reverse DNS.
>   #
>   # If your system can do DNS lookups without delay or cost, you might want
>   # to enable this.
>   # If sender_host_address is defined, it's a remote call.  If
>   # sender_host_name is not defined, then reverse lookup failed.  Use
>   # this instead of !verify = reverse_host_lookup to catch deferrals
>   # as well as outright failures.
>   .ifdef CHECK_RCPT_REVERSE_DNS
>   warn
>     message = X-Host-Lookup-Failed: Reverse DNS lookup failed for $sender_host_a
> ddress (${if eq{$host_lookup_failed}{1}{failed}{deferred}})
>      condition = ${if and{{def:sender_host_address}{!def:sender_host_name}}\
>                       {yes}{no}}
>   .endif


Note that this section merely sets a header, which you can then use in
your spamassassin rules if you like. If you want to deny (or defer)
outright on this condition, of course you can change the ACL.

- Marc