Milter-greylist

Milter greylist uses IP address as the first value of tuples.  With some big
domains and some ISP this is a problem because we could have a farm of SMTP
servers with many IP address.  This could cause long delay in mail delivery
process.

We avoid that by using  subnetmatch /24 in greylist.conf or -L 24 on the
command line. Then milter-greylist use only the first 24 bits of the IP
address for greylist matching when a mail comme again. Another solution
is whitelisting.

Improvements could be :

- both domain name and IP recorded and accept mail if one of them match
(with matching of the other values of course).

- a netmask depending on the IP class (/24 for C,  /16 for B , ? for A)
by using subnetmatch /0 or -L 0

- using SPF differently (actually if IP match SPF address then milter-greylist
accept the mail whithout greylisting)

For exemple with SPF we have good values of netmask and a list of all
possible IP :

club-internet.fr        text = "v=spf1 ip4:194.158.104.0/24 
ip4:194.158.107.10/31 ip4:194.158.96.0/24 ip4:194.158.99.10/31 ip4:213.44.120.91 
?all"

aol.com text = "v=spf1 ip4:152.163.225.0/24 ip4:205.188.139.0/24 
ip4:205.188.144.0/24 ip4:205.188.156.0/23 ip4:205.188.159.0/24 
ip4:64.12.136.0/23 ip4:64.12.138.0/24 ptr:mx.aol.com ?all"

aol.com text = "spf2.0/pra ip4:152.163.225.0/24 ip4:205.188.139.0/24 
ip4:205.188.144.0/24 ip4:205.188.156.0/23 ip4:205.188.159.0/24 
ip4:64.12.136.0/23 ip4:64.12.138.0/24 ptr:mx.aol.com ?all"

pobox.com       text = "v=spf1 mx mx:fallback-relay.%{d} a:webmail.%{d} 
a:smtp.%{d} a:outgoing.smtp.%{d} a:discard-reports.%{d} a:discards.%{d} mx:stor" 
"e.discard.%{d} a:emerald.%{d} redirect=%{l1r+}._at_.%{o}._spf.%{d}"

w3.org  text = "v=spf1 a mx ptr mx:sophia.inria.fr mx:inrialpes.fr 
ip4:128.30.52.0/22 ip4:133.27.228.192/26 ip4:212.89.0.17/28 
a:xana.fundacionctic.org a:www.w3c.es a:pec.etri.re.kr a:mta.prod1.dngr.net 
~all"


--
Christian Pélissier
Office National d'Études et de Recherches Aérospatiales BP 72 92322 Chatillon
Tel: 33 1 46 73 44 19, Fax: 33 1 46 73 41 50