[ILUG] Spam and more spam

Justin Mason jm at jmason.org
Wed Mar 3 01:07:42 GMT 2004


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Rick Moen writes:
>Quoting Justin Mason (jm at jmason.org):
>
>> Installing SA-Exim4 may be too invasive, though. :(
>
>I'm honestly not sure the above means.  (Please don't take that as my
>not being receptive to what you're saying.  A bit thick, perhaps. 
>Unreceptive, no.)

"invasive" in terms of sysadmin work required ;)

>Some significant advantages of MTA-level detection and handling:
>
>o  Your 55x rejects are guaranteed to be passed to the MTA that's 
>   actually trying to deliver mail to you.  This is a major gain 
>   compared with generating bounce messages, given the prevalence of
>   forged headers in incoming SMTP.  (In generating bounces to 
>   forgemail, you yourself as an MTA operator are a source of 
>   additional spam, not to mention wasting tremendous amounts
>   of bandwidth and processing power.)
>
>o  You can perform intelligent testing of the alleged sender _prior_ 
>   to accepting the mail.  E.g:
>
>    o  You can verify that sender domain has postmaster@ and abuse@
>       addresses, and accepts mail from a null reverse path 
>       ("MAIL FROM:<>"), as required by RFCs.
>    o  You can verify that alleged sender exists by initiating and
>       then cancelling a reply mail.
>    o  You can make sure sender or sender domain or sender IP are
>       not in various DNSBLs or site-specific blacklists.
>    o  You can optionally test the mail with SpamAssassin for
>       spamicity level.
>
>o  Based on such checks, you can for various cases, as the sender
>   or delivering MTA deserves, either accept the mail and deliver
>   it, or pretend to accept the mail and drop it on the floor, or
>   55x reject it, or teergrube (tarpit) the delivering MTA using 
>   45x SMTP messages.

That's true -- a very big plus for most people.

(Not me though, sadly.  in my case I have an interest in *receiving* spam
so I can record it for SpamAssassin development. that's life I guess ;)

Hmm -- Rick -- can SA-exim divert possible spam to a side mbox?

>> - - use MailMan 2.1.x  (MUCH better).
>
>As you'll note on
>http://linuxmafia.com/cgi-bin/mailman/listinfo/conspire , I _likewise_
>use Mailman 2.1.3.  While I appreciate its additional flexibility, I
>would not call it "much better" in the respects relevant to the problem:
>If the MTA accepts the junkmail, then Mailman still bothers the
>listadmin about it.
>
>Yes, you can indeed check "Discard all future mail from this sender",
>but that's not a lot of good, given that the junkmail's alleged sender
>was either random or effectively so.

yes.  But you can also check "allow all future mail" too, for the
genuine mail.  And the horrific web interface is avoided.

>> - - the nagmails for non-subscriber posts will arrive at the moderator
>>   list.  Have SEVERAL people on this list.
>
>Colm has explained why this is a poor outcome.  I agree.  So should you.
>The only solution is to ensure that the junkmail (in a very high
>percentage of cases) doesn't reach Mailman at all.  Thus my suggestion.

Hmm.   Given the volume Colm's talking about -- I would tend to agree.

>> FWIW, making sure that members can post freely helps a lot; the members
>> (the day to day community) are not impeded at all.
>
>But that is _not_ moderation, then.  Colm was speaking of list moderation, 
>something else entirely.

Sure, agreed.   I think Mailman may use the term "moderation" in
this situation though -- "moderated posting for non-members" or similar.

- --j.
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