>Imail needs a feature to limit the amount of emails that can be sent by an
>SMTP session based on IP in any specific time period. That would stop SPAM
>deliveries from and to Imail servers. Of course need the timeout penalty to
>be
>adjustable also.
>
>Why has this feature never been included?
Here is one POV on rate-limits is from www.ORBS.org:
Things which don't work - Rate limiting and limiting recipients per
message.
These don't work as relay control methods. They used to have some effect,
but all that
happens now is that spammers are relaying a few messages per server through
a lot of
servers in each spam run. It is actually resulting in the spam relay
problem becoming worse
again, because admins using rate limiting techniques or setting low maximum
numbers of
recipients believe that their machines are secured, so refuse to take
further action. While
individual machines become less abuseable, the overall effect on spam is
negligable - and
admins who limit messages to fewer than 20 recipients per message are only
succeeding in
irritating their own users. Most current spamware is capable of
automatically determining the
maximum number of recipients a server will allow, then sending to that many
per message.
Teergrubing is still effective to some degree for relay control, but only
when it used with
exponential backoff algorithms. In general it's easier to implement
external authentication
mechanisms. Teergrubing should only be attempted by those who have too much
spare time
and know exactly what they're doing. If you don't know what Teergrubing is,
you shouldn't
even consider it.
====================
Len
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