Kolab-users Digest, Vol 46, Issue 15

[Nik777]

> Subject:
> TO all anti-spam enthusiasts
> From:
> "Alain Spineux" <aspineux at gmail.com>
> Date:
> Thu, 13 Dec 2007 23:34:31 +0100
> To:
> "Kolab development coordination" <kolab-devel at kolab.org>, "Kolab 
> Users" <kolab-users at kolab.org>
>
> To:
> "Kolab development coordination" <kolab-devel at kolab.org>, "Kolab 
> Users" <kolab-users at kolab.org>
>
>
> Hi
>
> Recently, I saw a lot of post about activating some "postfix antispam" features.
>
> I would like to react!
>
> The first goal of an email system is to exchange messages between peoples.
> Anything that prevent messages to pass through must be discuss with care!
> [...]
> Only grey and black listing are "dynamic" measures against SPAM that
> SPAMMER cannot control!
>
> Regards
>   
I couldn't agree more.

I recently implemented greylisting for one of our email domains, and the 
results were amazing! Of 11041 emails received in the following 24 
hours, 40 were actually delivered. The remaining 1101 did not retry!

I am now looking for a more sophisticated  greylisting implementation 
which would allow me to recognise some further spamming behaviour in a 
fully dynamic way.

For instance, recognising multiple emails from the same IP address to 
different invalid addresses on our domain.

In all other areas of my firewall, I also only implement dynamic 
blocking, so that suspicious behaviour is blocked temporarily, which 
protects my network, but then the block is removed, so that I don't 
later block potentially correct traffic.

Cheers!
Nik