Date: Sun, 08 Apr 2007 19:16:28 +0200 From: Erik Norgaard <norgaard@locolomo.org> To: Angelin Lalev <lalev@uni-svishtov.bg> Cc: freebsd-questions@freebsd.org Subject: Re: advice on anti-spam tools Message-ID: <4619236C.9040407@locolomo.org> In-Reply-To: <0875b56eeca4d320fd9fa7b0d940fce2@uni-svishtov.bg> References: <0875b56eeca4d320fd9fa7b0d940fce2@uni-svishtov.bg>
next in thread | previous in thread | raw e-mail | index | archive | help
This is a cryptographically signed message in MIME format.
--------------ms000808030003080300030708
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Angelin Lalev wrote:
> Hi List,
>
> My e-mail server is running the latest spamassassin with all of the blacklist enabled and etc.
> but I still receive over 20 spam messages a day ("image" spam mostly).
> The situation with other users may be worse. That's why I was thinking about some tool that
> 1. store incoming email
> 2. send request to the sender of the message, requiring to go to some address and enter the numbers (letters)
> from image
> 3. if the puzzle is solved in time (week or so) deliver the message, otherwise delete it.
>
> Is there such tool(s) ?
I use grey listing and spamhaus xbl, no spamassasin or content analysis.
Apart from grey listing and spamhaus, I block in my firewall IP ranges I
have found un trustable, particular China and Korea, and ranges assigned
dynamically, and I have some header analysis rules.
I get about 2 spam mails a day.
The earlier you can reject a message the less resources it takes, see
how much you can reject on the envelope rather than data.
I have found that many spammers use my servers name or IP in HELO, so I
reject that. Also, reject unresolvable domains etc, simple stuff.
Really, if you want to effectively address the problems, store all spam,
create a spambox for users to forward their spam to. Analyse it every
now and then. For example I did this to idenfity IP ranges sending spam.
With greylisting, I have found that greylisting 5 minutes will delay
mail significantly and some mail will not be delivered. 3 minutes seems
better.
Cheers, Erik
--
Ph: +34.666334818 web: http://www.locolomo.org
--------------ms000808030003080300030708
Content-Type: application/x-pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature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--------------ms000808030003080300030708--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4619236C.9040407>