I want to put a rule in my ACLs that will deny relaying from/to the same
domain. All the server does is relaying so all the allowed domains are in
dc_relay_domains. I think I want to put something like
Drop $sender_address_domain= $domain in the acl_smtp_connect ACLs
Is that the right rule and is that the right place to put it?
The exim server is a backup relay for multiple separate domains running MS
exchange, I don't want any real anti-spam on the server but currently it is
being used to backscatter the exchange servers. While mail could
legitimately be from one host to another, no internal emails will ever be
going though the server, so this rule will prevent plenty of SPAM but can't
possibly catch HAM. Is there a better way to do what I want? Am I right
thinking it will work?
Juan Canham
Tel: 0800 2922 230
Fax: 0207 265 0249
Email: mailto:Juan@supporttree.co.uk
Web: www.supporttree.co.uk
18A Ensign Street London
E1 8JD
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Date: Sat, 10 Jul 2010 09:34:44 +0100
From: Dave Evans <exim-users-20081202@???>
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Subject: Re: [exim] Denying mail from the same domain
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On Fri, Jul 09, 2010 at 06:38:48PM +0100, Juan Canham wrote:
> I want to put a rule in my ACLs that will deny relaying from/to the same
> domain. All the server does is relaying so all the allowed domains are in
> dc_relay_domains. I think I want to put something like
>
> Drop $sender_address_domain= $domain in the acl_smtp_connect ACLs
>
> Is that the right rule and is that the right place to put it?
If you want to compare the sender's address to the recipient's, then the ACL
will need to be at acl_smtp_rcpt time (or possibly later); something like
deny
condition = ${if eq{$domain}{$sender_address_domain}}
message = I don't like the look of you
should work.
That said, in the *general case* this can definitely end up blocking legit
mail, so personally I wouldn't use it. Whether it would do so for your
*specific* case though, I can't say.
Other approaches may well be worth the extra effort (e.g.: have Exim as the
MX, with spam filtering, with the Exchange servers behind; or only activate
the dumb relay servers if the Exchange server goes down).
Having a lower-priority MX server which has spam filtering inferior to its
higher-priority counterparts tends to produce disappointing results.
--
Dave Evans
http://djce.org.uk/
http://djce.org.uk/pgpkey
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