North American Network Operators Group

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Misguided SPAM Filtering techniques

  • From: Owen DeLong
  • Date: Sun Oct 21 00:55:41 2007

I'm seeing an increasing variety of misguided SPAM blocking techniques such
that they are starting to become more and more annoying, and, I'm curious as
to what solutions/work-arounds others have deployed, and, if anyone has any
ideas on how to get these tactics reduced/stopped?

Here's the primary hinderance.

I use an authenticated TLS-protected mailhost at home for submitting my
email for delivery.  Unfortunately, networks have taken to:

	outright blocking 25 and 587 except to their own servers.
	proxying all 25/587 connections in a manner incompatible with TLS
	proxying all 25/587 connections in a manner incompatible with SMTPAUTH
	blocking TLS startup on 25/587 connections

Primarily, I have run up against this in the following networks:

	SPRINT Cellular network (can no longer send email from my phone)
	Public wireless networks
	Hotel networks
	Other WiFi hotspots
	Some DSL providers networks

I can't imagine that these tactics actually do anything to significantly reduce
the amount of spam delivered to the internet, so, I'm curious as to:

	1.	Why are they used?
	2.	How do we convince operators to abandon them?
	3.	How prevalent is this problem, and, is it growing as I perceive?