Re: [PLUG] Postscreen (another tool for helping to minimize the effect of spam)

["Keith C. Perry" <kperry@daotechnologies.com>]

I learned that years ago after at the apex of some spam issues my DNS traffic was running ridiculous high do to some windows front end boxes, web, mail and some other things.  'Started using recursive caches and boom, the network was like new.  You almost had to do this towards the the end of the T1 internet days.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 
Keith C. Perry, MS E.E. 
Owner, DAO Technologies LLC 
(O) +1.215.525.4165 x2033 
(M) +1.215.432.5167 
www.daotechnologies.com

----- Original Message -----
From: "Rich Kulawiec" <rsk@gsp.org>
To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
Sent: Monday, October 24, 2016 5:54:42 PM
Subject: Re: [PLUG] Postscreen (another tool for helping to minimize the effect of spam)

On Mon, Oct 24, 2016 at 05:33:48PM -0400, Keith C. Perry wrote:
> That doesn't quite make sense. The DNS lookups are going to get cached. 

[snip]

Yes. They are.  This is why I recommend running a recursive caching
resolver (that only responds to connections from localhost) on each mail
server, whether it's inbound, outbound, or both.  (Of course in larger
configurations, that recommendation gets modified a bit.)  How large
the cache should be depends on the operational characteristics of the
mail server -- in particular, on the diversity of sources and sinks for
SMTP connections.

This also makes it possible to readily utilize DNS RPZ in conjunction
with the mail system.

---rsk
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