Re: [exim] Preventing TXT lookups after successful acl modif…

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Author: Mar Matthias Darin
Date:  
To: Mike Cardwell
CC: Exim Users List
Subject: Re: [exim] Preventing TXT lookups after successful acl modifier dnslists processing
Hello,

Mike Cardwell writes:

> Instead of using "dnslists", you could perhaps use the dnsdb lookup type
> as a workaround. Example
>
> REVERSE_SENDER_IP =
> ${sg{$sender_host_address}{\N^(\d+)\.(\d+)\.(\d+)\.(\d+)$\N}{\$4\.\$3\.\$2\.\$1}}
>
> That creates a macro which returns $sender_host_address with the octets
> reversed. Then do:
>
> condition = ${lookup
> dnsdb{defer_never,REVERSE_SENDER_IP.zen.spamhaus.org}{true}{false}}
>
> This is equivalent to:
>
> dnslists = zen.spamhaus.org


DynaStop does this automatically and returns a code (a code 2) just for
non-reversible domains (RDN). The results are cached generating a big
saving in DNS queries and bandwith. I average 80% cache hit ratio from
DynaStop (YMMW though). DynaStop can alternatively greylist non-RDNs for
any given period if prefered.

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DynaStop: Stopping spam one dynamic IP address at a time.
http://tanaya.net/DynaStop/