I don't see the emails from the list.

[Bill Campbell]

On Sat, Sep 29, 2007, Jay R. Ashworth wrote:
>On Wed, Sep 26, 2007 at 09:46:50AM -0700, Bill Campbell wrote:
>> Some ISPs are using ``grey listing'', a process in which messages
>> are initially rejected with a 400 series SMTP message, later to
>> be accepted.  The idea is that legitimate MTAs (Mail Transport
>> Agents) will retry later while spammer's malware probably won't.
>> This may result in delays sending messages to these ISPs.
>
>The definition of greylisting that I have seen (and which I use, and
>which doesn't work all that well anymore) is to put a higher-priority
>MX pointed at a machine that doesn't accept incoming TCP/25 -- or
>better yet, behind a firewall which ignores it.

I dont' see how that would work (MX priority is best thought of
as distance as the lower numbers are preferred).  Often spamware
tried hitting the higher distance MX servers in hopes that
they're not as well protected or use different filters than the
primary MX server.  Other spamware seems to have MX servers hard
coded ad I see attempts to deliver to systems here that haven't
been MX servers for a decade or so.

Our largest regional ISP customer only lists a single MX server
which handles all their incoming mail.  If there's a problem with
that machine, we can change the DNS to have it go to another
server in minutes.  This prevents spammers from simply trying
multiple MX servers, only to be rejected by them as well.  The
single MX server rejects about a million attempts a day using
various IP level checks.  It runs postfix, amavisd-new, and
clamav to do anti-virus and phishing checks, passing clean
message to a cluster of five machines that do spamassassin
checking and delivery to their customer's Maildir boxes.

The load average on the primary MX server averages less than 1.00
even with that volume of messages.  This machine isn't what would
be considered high-powered today, an Intel(R) Pentium(R) 4 CPU
3.20GHz with 2GB RAM running SuSE Linux Enterprise 9.

Bill
--
INTERNET:   bill at celestial.com  Bill Campbell; Celestial Software LLC
URL: http://www.celestial.com/  PO Box 820; 6641 E. Mercer Way
FAX:            (206) 232-9186  Mercer Island, WA 98040-0820; (206) 236-1676

Cutting the space budget really restores my faith in humanity.  It
eliminates dreams, goals, and ideals and lets us get straight to the
business of hate, debauchery, and self-annihilation.
		-- Johnny Hart