Re: [exim] Blocking hosts without MX/A records in DNS

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Auteur: Exim users mailing list
Datum:  
Aan: Luca Bertoncello
CC: Exim-Users ML
Onderwerp: Re: [exim] Blocking hosts without MX/A records in DNS
On Mon, Jan 08, 2007 at 11:16:14AM +0100, Luca Bertoncello wrote:
> Hi, list!
>
> In order to try to reduce the (huge!) quantity of daily spam, we want to
> reject the E-Mails coming from domains which do NOT have a valid MX or
> A record (aka: the domain does not exist, or is not fully configured).
>
> I thought, verify = sender do that, but it doesn't... :(
> How can I implement this check? I use Exim 4.62.


A simple way to check the existence of MX records for sender's domain
is to use dnsdb lookup in rcpt ACL:

        deny   
                message         = Mail from domains without MX!
                condition       = ${if eq{${lookup dnsdb{mx=$sender_address_domain}{$value}}}{}}


I think this is should be used with caution. In order to avoid denials
of legal messages you may to replace 'deny' verb with 'warn' and
watch mail log.

As regards the A records I guess the 'verify = sender' should check this.

Good Luck!

-- 
Kind Regards,    Alexander Shikoff
minotaur@???
Mob.: +380 67 946 31 49