North American Network Operators Group

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Re: Anyone with SMTP clue at Verizon Wireless / Vtext?

  • From: Rich Kulawiec
  • Date: Thu Feb 08 08:47:36 2007

On Wed, Feb 07, 2007 at 06:25:41PM -0800, Mike Lyon wrote:
> Their gateway is blocking mail from my host. Of course, there is no
> clueful contact info on their webpage...

I know you asked for off-list, but since this (mail to Verizon
refused) is a recurring problem, I'm sending this on-list as well.

Anyone who has trouble sending mail to Verizon should check their
own *incoming* mail logs for connections coming from systems in (GTEN-206-46), most likely, whose
names look something like:

If you're refusing those connections or blocking mail RCPT TO
attempts from them, then Verizon will probably refuse your outbound
SMTP traffic to them.

This may not be the problem you're facing; or it may not be the
only problem you're facing.  But it's easy enough to check and
rule out if that's the case.


p.s. *Why* is this happening?  Because Verizon has deployed a
very ill-considered "anti-spam" technique ("callbacks" AKA
"sender address verification") that serves three primary functions:
first, it forcibly shifts the costs of Verizon's spam control onto
third parties; second, it provides a spam support service; and third,
it provides a free, anonymizing, scalable DDoS service.