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more on Comcast blocking personal mail servers
From: David Farber <dave () farber net>
Date: Sun, 9 Apr 2006 19:08:27 -0400



Begin forwarded message:

From: Ron Guerin <ron () vnetworx net>
Date: April 9, 2006 7:03:35 PM EDT
To: alberti () sanction net
Cc: dave () farber net
Subject: Re: [IP] more on Comcast blocking personal mail servers

Robert Alberti wrote:
From: Ron Guerin <ron () vnetworx net>
You don't mention who your ISP is, however, if Comcast is under the
impression you're on a residential IP address, odds are they got this
information from _your_ ISP, who is, in effect, telling Comcast to block
your mail.  Does your agreement with your ISP prohibit the running of
servers from your account? If so, you have your answer, which is that you're violating your agreement, and Comcast knows this because your ISP has published their residential IP addresses for the express purpose of allowing other ISPs to refuse mail coming from those addresses. If your service agreement does not prohibit the operation of servers, you still should investigate whether your ISP has published their residential IP
space for blocking purposes.  Many, if not most residential blocking
lists are based on self-published IP ranges.

I have a static DSL IP from visi.com which permits the operation of
servers on my account.  I suspect although I do not know for sure (nor
did the Visi technician to whom I spoke) that the fact that my reverse
DNS name is "sanction.dsl.visi.com" that either the discrepancy between
my mailhost name "sanction.net" or the presence of 'dsl' in the string
are triggering the rejection.  I'm trying a reverse-DNS of
'sanction.net' to see if this fixes the problem.

That may well fix your problem.  It all depends on the policy over at
Comcast, which as you say, is in all probability, unpublished.  I do
know of some who attempt to dynamically block based on parsing the
returned value of the reverse lookup, and indeed, it is considered a
sign of both competence and intent to run a mail server by some mail
service providers if you've had your reverse lookup changed to
something not "generic" to the given ISP.  As a last resort, you could
try contacting Comcast for a whitelisting.  Given that you are not
prohibited from running servers, you certainly have grounds to protest
your blocking.

I like Karl's solution of obtaining a block of IP addresses from Jon
Postel, however the hereafter keeps rejecting my e-mail requests for a
block of my own.

I wish we all had what Karl has. At least I wish *I* did. ;)

- Ron


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