[Dshield] ISP's blocking dynamic IP address mail servers

Micheal Patterson micheal at tsgincorporated.com
Thu Apr 22 14:53:19 GMT 2004

----- Original Message ----- 
From: "Rick Klinge" <rick at jaray.net>
To: "'General DShield Discussion List'" <list at lists.dshield.org>
Sent: Wednesday, April 21, 2004 7:21 PM
Subject: RE: [Dshield] ISP's blocking dynamic IP address mail servers

> > > dynamic ip range that these systems are using. Cox Cable
> > for one, and
> > > I've seen mention that others may follow suit, are starting to even
> > > prevent
> > their
> > > clients from sending and receiving to port 25 off their network to
> > > curb
> > this
> > > problem forcing clients to use their specified mail servers for
> > > sending mail.
> >
> > Unfortunately, that leads to a real problem if the ISP's mail
> > server starts dropping emails, like Cox's is right now.
> > Soon, I'll be requesting two weeks refund for non-working
> > email.  And they'll have to give it to me, because they are
> > blocking the ability to send email to anyone.
> >
> Is this is on a business class connection?  I haven't had any issues
> Cox assign rDNS, etc, for email.  The only 'slight' worry I have is they
> always seem to back-scan sending ip addresses to there domains.  I do
> that Comcast, in the US, should block all email i/o from anywhere within
> there direct control.  They seem unable to adequately control their
> infrastructure - concerning email.
> ~Rick

They're doing it on the Residential connections in my area. The business
circuits aren't supposed to be touched. As for ComCast, they can fall
through to the earth's core as far as I'm concerned. 85% of my bogus email
is from within their network and attempts to get them to take action are
apparently totally ignored. I have a ruleset in my firewall that I enable
when they start getting out of line.


Micheal Patterson
TSG Network Administration

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