[e2e] Fwd: Camel's nose in the tent

[stanislav shalunov]

Vernon Schryver <vjs at calcite.rhyolite.com> writes:

> Does that policy apply to all SMTP traffic or only to SMTP sessions
> with Verizon DSL SMTP relays or servers?  In other words, are they
> simply limiting the end-to-end traffic between their hosts (that
> happen to be an SMTP relays) and other hosts or are they running
> interception proxies?

I believe they block outgoing connections to port 25 (as many other
ISPs do).  So, you have to use one of their servers to send mail
(unless, of course, you have a setup like mine where you tunnel to the
office).  Apparently (I'm not their customer), their servers will
block mail that contains "From:" header that the relay doesn't like.

While it's entirely their option to block mail based on arbitrary
criteria, including "From:" headers or anything else (as it is the
option of their users to avoid ISPs that annoy their own users), and I
don't see any great violation of engineering principles of SMTP here
(there *would* be a serious violation of these principles if they
replaced your "From:" line with what they think is the correct line),
it's definitely a poor practice.  A far better spam-combating
technique would be to make sure the ``correct'' address
(verizon-username-as-determined-from-IP at verizon.whatever) appears in
the headers.  One could put it in the received line (prepend the
username to the originating IP) or insert a "Sender:" header, or
insert an X- header.  This would provide accountability without
interfering with users' ability to use addresses they like.

-- 
Stanislav Shalunov		http://www.internet2.edu/~shalunov/

Most people can do nothing at all well.              -- G. H. Hardy