On Wed, 18 Aug 2004, Rodolfo Sikora wrote:
Well, I'm managing about 1.5 million email boxes right now, and I can
say SMTP AUTH does the job. If someone starts to spam, u can lock it
out.
And I have been blocking the whole comcast, ameritech, verison dsl
networks. 80% of my incoming spam is comming through these providers.
I guess that serious people uses smtp auth.
No, it's that a lot of spammers/viruses/etc. use zombied machines
which are fairly prevalent in the Comcast/Ameritech/Verizon
world. They're concerned, correctly, that if they cut off ports and
restrict services, even if their contracts allow them to do so, that
aggravated clients and civil liberties advocates will make their lives
hell in court.
Also, allowing services for those business customers who contract to
run their own SMTP server, SQL server, FTP server, IRC server,
etc. over the Internet at large and writing the filter rules to allow
the corporate customers but not the home customers is a serious
manpower sink. It's often very easy to screw up the rules and leave
gaping holes or cut off people without warning, and the engineering
time and router CPU resources eat up your limited budget. ISP's are
still going out of business at a regular rate, even fairly large ones.
I'm going to use SPF not to block email, but to whitelist emails so my
anti spam solution won't touch these "ham" email.
If my system detect a spam from a domain using SPF, this domain will
be blocked automatcly.
Good stuff. Unfortunately, it's easy for a reputable and responsible
network to accidentally get a virus-laden or zombied machine, so I
hope you're leaving a reasonable amount of slack for such accidents.
--
Nico Kadel-Garcia
Systems Engineer
Mitsubish Electric Research Lab
<nkadel(_at_)merl(_dot_)com>