On Sat, Apr 26, 2003 at 11:49:41PM -0600, Vernon Schryver allegedly wrote:
From: Scott Nelson <scott(_at_)spamwolf(_dot_)com>
...
Designated Sender stuff...
The problem with that is that Hotmail, Yahoo, and most of the rest of
the owners of the domain names that appear in SMTP Mail_From senders
in the majority of spam instruct their DNS servers to always answer
"yes, a.b.c.d authorized" for any and all IP addresses.
I doubt it. They suffer hugely from bogus addresses in their domain
space and anything that reduces the huge bounceback plus reduces their
abuse load plus reduces the bad press they get from appearing to be a
spam haven will be seen as a good thing.
As far as I can tell almost all free mail providers not only
allow but encourage their users to send their mail using the
ISPs that provide connectivity.
Not so. Especially given that most of the free providers still get a
lost of their revenue stream from having eyeballs look at their web
pages while composing and sending email.
Evidence of this is that port 25/110 access - when provided by
freemail providers - is now mostly only done so on a fee basis to
compensate for lost eyeballs (admittedly that's also an anti-abuse
strategy but it's not the only reason).
- It is cheaper for the free mail providers to let someone else
provide the bandwidth, CPU cycles, and so forth to send mail.
Marginally so, but unlikely to be a dominating factor. Outbound mail
from freemail providers is typically swamped by the web traffic and
inbound mail/spam. Consider that a single page view of a single email,
heavily laden with ads is what, 5-10 times bigger than the average
outbound mail?
- Many free mail provider users cannot send mail through their free
providers, because their connectivity providers block port 25.
That is true and unfortunate collateral damage. I wish that RFC2476
was written with a "MUST AUTHENTICATE" and was more widely deployed so
that connectivity providers could safely leave port 587 open.
Various forms of roaming including using your laptop in airports and
varying IP addresses provided with DHCP or IPCP to dialup, DSL, and
cable modems make it impractical for free providers to know their
customers well enough to know which IP addresses each will use.
That is true, but I don't think you should under-estimate the benefit
freemail providers perceived in a designated sender scheme. I do work
for a large provider and speak to others - the bad press, the abuse
load and the bounceback loads are significant factors that add to the
appeal of developing and deploying a workable DS scheme.
Regards.
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