Re: [exim] anti-spam... what's next?

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Author: Kjetil Torgrim Homme
Date:  
To: Steve Kemp
CC: exim-users
Subject: Re: [exim] anti-spam... what's next?
On Tue, 2008-11-18 at 17:22 +0000, Steve Kemp wrote:
> Other tests that are good for rejection:
>
>     * Bogus Message-IDs.
>       (Validate the header is present and you're 99% of the way there.)


Message-ID is not a required header, this will lose legitimate mail.

>     * Dialup range restrictions .
>       (Guess you've got that covered already via DNSRBL)

>
>     * Early-talker
>       (Machines that send conversation before waiting for the banner.)

>
>     * Make sure there is a Date: header.
>       (I do range testing on that; but many spam mails don't have it
>       c.f. message-id:)


the Date: header *is* mandatory, so this is fine :-)

>     * HELO checks
>       (I mostly look for helo $my_IP)


unqualified addresses (no dots) are illegal, and stop a lot of broken
spam software. bare IP addresses likewise, they need to be in brackets,
e.g, "EHLO [10.20.30.40]".

-- 
regards,          | Redpill  _
Kjetil T. Homme   | Linpro  (_)