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Matt,
You
have some very good points, but they can be countered easily with a good
plan. :) For example:
The
ISPs obviously wouldn't/shouldn't block port 25 without notifying people.
All that would be needed is to set a date that they would begin doing so, thus
giving everyone ample time to get on an internal "allowed" list if needed.
After that date, their abuse department (if they truely have one) will have
about 70% less work to do. With all of the extra time they have, they can
then begin to get their heads above water with the abuse complaints.
Outbound mail can then be throttled to reduce the effects of these zombies, and
as you said, implement a tarpit measure to temporarily freeze these machines
from sending for a period of time.
With
the ISP having an "authorized" port 25 allowed, your business model is no longer
affected (other than a very minor "please allow port 25 for X user").
Also, I don't think that blocking port 25 with this "allowed" list is lazy, it
is a very effective way of keeping your (said ISP) problems from infecting the
rest of the internet. They could even think of it as good PR.
:)
Jason
Jason,
Spammers are now using zombies to relay
through their ISP's mail servers which is problematic because you don't want
to blacklist an ISP mail server (though SpamCop does this all the time).
If everyone starts blocking outbound port 25, it will cause this practice to
become even more common.
As an E-mail provider I can also tell you that
this is very problematic for my business. I have taken hours to diagnose
conditions where an ISP started blocking port 25 unannounced, and I have also
had to deal with many less savvy people that think that I am responsible for
their outgoing E-mail when they are using the server of their ISP. I
started offering E-mail services several years ago after getting tired of
trying to deal with various ISP support lines to fix my customer's issues, and
I don't wish to go back to that.
There are methods other than blocking
port 25 that can be used without impacting the customer or businesses such as
mine, such as monitoring for excessive use and then cutting off the IP and or
account. Blocking port 25 is a lazy way of resolving the spam problem,
i.e. hitting a nail with a sledgehammer.
Matt
Jason
wrote:
Blocking subscriber networks is a wonderfull idea, but as many have
pointed out, it doesn't work in the real world. The real answer is to
have the offending ISPs block port 25 from their subcribing nets. This
achieves the same result, and forces the ISP to take responsibility for
spam.
That being said, the only way to do this is for everyone to start
ruffling feathers at said ISPs (not going back and forth on this list).
The best way to do this is to get the word out, talk to your local TV
stations, get radio interviews, get the word out to the un-knowing
public that there is a way to curb a LOT of this spam. Right now,
everyone (Joe Public) thinks that there is nothing they can do about it,
and that is just wrong. There is a lot that can be done, but they just
need to know their options.
Regards,
Jason
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of Panda
Consulting S.A. Luis Alberto Arango
Sent: Friday, February 13, 2004 8:25 PM
To: [EMAIL PROTECTED]
Subject: RE: [IMail Forum] Error 554?
Just my thoughts:
We prefer to have all spam come into our customers mailboxes and rather
look for a local antispam solution at the users end.
We manage 130 different domains from companies doing business with many
countries around the world.
If I block IPs (using a blacklist) and by any chance one good email is
blocked then murphy's law stars playing its part... and the good mail
was for the CEO of the company and is the want he was waiting for with
the information to win a multibillion contract with the government...
so.. somebody will be very mad at us...
We haven't find any good proven solution to prevent spamming but
Blocking IPs is not an option.
And looking at the other side of the page, it is quite frustrating when
your customer calls you telling you that somebody out there is not
getting their emails because our Ips are in the black list.
Then you find out that you were blacklisted because your IP is part of a
block owned by Verio, and there is this boycott thing against Verio...
so at the end it is your fault to have an IP owned by Verio. Doesn't
sound fair to me, but such is life...
-Luis
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of Len Conrad
Sent: Friday, February 13, 2004 1:45 PM
To: [EMAIL PROTECTED]
Subject: RE: [IMail Forum] Error 554?
Is this becoming common practice to just deny entire IP address blocks
due to listings on spam databases?
Sure, if your MXs statistics show that 5 or 10 addresses from a Class C
are
abusing you, then you have every right to block the entire Class C.
The network operator responsible for the Class is not policing his
network,
so your concluding that other IPs in that Class will sooner or later
also
be spamming you is valid.
A good analogy is that the network operator is operating a factory that
is
spewig crap that is polluting your air, so you boycott all that
factory's
products.
This is the logic behind blocking "subscriber" networks by PTR hostname
and
by HELO hostname. Your MX is receiving 10's of 1000's of spams from
charter/att/comcast/rr/telus/pacbell/sbd/etc/etc/etc networks, for
every handful, if any, of valid msgs, so you block all those subscriber
networks until those multi-$$billion network factories, which huge,
highly
competent, highly paid IT staffs, stop polluting your email environment.
Len
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