OT - Greylisting (was: Re: gOCR SpamAssassin plugin)

[mikea]

On Fri, Aug 11, 2006 at 01:05:18PM -0400, Michael Baird wrote:
> On Fri, 2006-08-11 at 10:52 -0500, Logan Shaw wrote:
> > On Fri, 11 Aug 2006, Jim Holland wrote:
> > > Another concern is the impact that greylisting would have on the Internet
> > > if its adoption became widespread - it would mean that all mail servers
> > > would have to work twice as hard to deliver mail.
> > 
> > Actually, it's only some mail servers.  Greylisting lets known
> > senders through without a delay.  Mail servers that are mostly
> > sending messages to recipients who recognize them would not
> > see delays.  Mail servers that are mostly sending messages
> > to those who don't recognize them would see the delays.  So,
> > it makes mail servers up to twice as hard.
> > 
> > Also, while I agree that it would increase the load, in
> > general I think decreasing spam is worth some increased load.
> > Sure, it's a slippery slope (one could imagine things getting
> > so bloated that it takes 5 minutes of CPU time to deliver one
> > message, if we keep on adding limitless spam-fighting strategy),
> > but on the other hand, 10 seconds of CPU time spent catching
> > spam automatically is cheaper than 10 seconds of a human's
> > time deleting it manually.
> Greylisting decreases load immeasurably on a mailscanner system, the
> cost of greylisting is much less then allowing the message to go through
> the mailscanner sytem. I deployed it several months ago, it really is a
> good tool, and I've had very few complaints (10000 users).

My complaints have, almost without exception, come from users who think
that E-mail should show up in their inboxes Right DamnIt _NOW_. There 
have been a few cases in which the sender's system has mishandled the 
retry or totally failed to retry; I've whitelisted some of those, and
the rest were non-work-related and so could go hang[1].

[1]  It's a corporate mailsystem, not an ISP, and the policy is that 
     employees get to use it for personal purposes, but if their 
     personal mail gets blocked as a result of our filters, that's 
     just too bad. 

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin