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

[Rich Kulawiec <rsk () gsp org>]

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
206.46.0.0/16 (GTEN-206-46), most likely 206.46.252.0/24, whose
names look something like:

        206.46.252.147  sv114pub.verizon.net
        206.46.252.148  sv124pub.verizon.net
        206.46.252.149  sv134pub.verizon.net

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.

---Rsk

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.