Re[2]: [Exim] Re: Request for anti-spam feature in exim4

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Autor: Sharun
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A: Matthew Byng-Maddick
CC: exim-users
Assumpte: Re[2]: [Exim] Re: Request for anti-spam feature in exim4
Okay, I solve this problem with couple of external scripts. Interesting ?
2 hours of work = 250 hosts in my RBL :))

------------- Original message -----------
> From: exim@???
> To: exim-users@???
> Subject: [Exim] Re: Request for anti-spam feature in exim4
> Date: Wednesday, December 05, 2001 at 14:39


MBM> On Wed, Dec 05, 2001 at 12:18:24PM +0000, Drav Sloan wrote:
>> Suresh Ramasubramanian wrote:
>> > There are plenty of third party blocklists available for this - which can be
>> > queried using exim.
>> Of which I'd argue the majority are mostly useless/out of date/have
>> very bad policies/will not listen to the public.


MBM> Yes. I agree with this.


>> I also would agree with Sharun; I'd like to see the ability for exim
>> to maintain it's own db of 'open relays' by verifying this at connection
>> time from other hosts - (very much like the verify_recipients option).


MBM> Erm? You mean doing a callback to test for open relay? Are you completely
MBM> insane, or completely clueless? There are several reasons not to do this.


MBM> 1) it is hostile to mailadmins who maintain clean machines.
MBM> 2) you're assuming that a relay can be delivered straight away, or that
MBM>    acceptance of responsibility for the message is an indication of that
MBM>    machine being about to relay it.
MBM> 3) you will probably get the tests wrong, think of the time when 127.0.0.1
MBM>    hit the MAPS RSS, and loads of people started generating X-RBL-Warning
MBM>    headers, which were (incorrectly) rejected by other people's mail
MBM>    filters.
MBM> 4) you will waste enormous amounts of bandwidth.


>> Is there similar, has anyone heard of anyone managing to impliment this?


MBM> If you just delay messages[1] initially, and change the delay parameters
MBM> depending on what lists they are on, rather than outright rejecting them
MBM> things work a bit better. Often this means that other people complain
MBM> about the spam run and the machine gets pulled.


MBM> [1] by issuing a 450 in response to the RCPT TO:< line in the SMTP dialogue.


MBM> I've found this trick works extremely well...


MBM> of course,


MBM> 5) you will have problems with anybody who implements such a system on their
MBM>    mailserver, as you'll have to wait to be able to test it.


MBM> MBM