greylisting

[Craig White]

On Wed, 2007-02-07 at 10:04 -0500, Jeffrey Ross wrote:
> 
> Craig White wrote:
> > On Tue, 2007-02-06 at 07:56 -0500, dhottinger at harrisonburg.k12.va.us
> > wrote:
> >   
> >> I got greylisting running last night on my mailserver.  Seems to have  
> >> cut the number of posts to my mailman mailing lists quite a bit.  I  
> >> had well over 700 posts I had to discard the past 3 days and this  
> >> morning I had 3.  As far as I can tell all mail is coming in to my  
> >> 750+ users also.  Im using relaydely and sendmail.  Wasnt to hard to  
> >> get going.  Readme and files included are a little vague, but finally  
> >> got the right perl packages in and its up and running.  I'll keep an  
> >> eye on it the next few days and see.  What kind of delay is everyone  
> >> using for this?  All yea, Im running Fedora Core 6, most of my  
> >> packages are from install.  I have installed some perl modules and did  
> >> some yum updates, so everything is up to par.
> >>     
> > ----
> > I use 5 minutes
> >
> > FWIW - I left sendmail/relaydelay a few years ago in favor of
> > postfix/sqlgrey/mailscanner/spamassassin/clamav and it's worked very
> > well.
> >
> > Craig
> >   
> 
> I tried greylisting as well, I am using exim as my MTA.  I found that 
> although greylisting worked, I found nightly updating the rules for 
> spamassassin worked better they greylisting and as such have dropped the 
> greylisting.
> 
> Just my experience, your mileage may vary
----
I think the point of greylisting is to block incoming mail from
compromised desktop systems that are not true SMTP servers exploiting
the fact that these compromised systems are optimized to deliver large
amounts of e-mail and not keep track of things like TEMPFAIL where a
real SMTP server will. Also - and perhaps the most significant issue is
that spamassassin is a real resource hog and if greylisting removes
70-90% of inbound mail from ever being processed by spamassassin, the
load factor on the system running spamassasin is significantly reduced.

Whatever floats your boat.

Craig