[Cadre-politics] forward: note re SMTP connection rejection

[Stéphane Alnet]

> Below is a strong argument for rejecting mail at SMTP time, not
> accepting the message in the first place. The problem (as Craig Sanders
> points out in a different thread on debian-isp) is that we lose the
> ability to queue.

One option that cuts down on spam at the SMTP level without requiring
much processing power is greylisting. Postgrey[1] is a good
implementation if you are using postfix. Greylisting is basically
targetted at disrupting email bots but keep regular, SMTP-compliant
MTAs happy. One can combine greylisting with further (existing) spam
control in the back as usual.

[1] http://isg.ee.ethz.ch/tools/postgrey/

One argument _against_ greylisting that was given to me by an ISP
friend (and given that CSL is an ASP I think this could be a valid
concern) is that emails get delayed significantly the first time a
legitimate, external sender emails a given recipient (using
greylisting). Explaining the inbound delay issue versus the benefits
of greylisting (dramatic decrease in spam) requires marketing (or at
least proactively "selling" the solution to your users before
implementing it).

Just a thought,
Stéphane

-- 
http://www.linkedin.com/in/stephalnet