On Fri, 27 Jan 2006, Douglas Campbell wrote:
Daniel Feenberg:
Of these only 874 (13%) had an existing RDNS that did not reek of dynamic
assignment. That is, did not include the strings "dsl", "dynamic", "dial"
or "pool" and did not have any all-digit components.
I have one of the aforementioned addresses; my rDNS is
h-69-3-215-47.lsanca54.covad.net. Obviously, I would be averse to
having the rule you state run a widely used blocklist, but each of us
must run our installations as we see fit. If I see my address widely
blocked, I'd consider routing my mail through my ISP; the only reason I
don't is that I'm running sendmail, it's full featured, and I don't see
a good reason yet to take the extra hop via a remailer. My ability to
send you e-mail is a privilege, not a right, and you have the right to
deny me that privilege.
That said, such a rule tars the innocent along with the guilty. It's
like a google search that is over-broad. Think. We can do better.
Yeh, I am aware that some static addresses have dynamic sounding names.
The strings of digits are the most commonly misleading sign, but they
account for about half the dynamic sounding addresses, which makes it hard
to leave them out. It would be possible in principle to maintain a list of
truely dynamic addresses, but it would be a continuous effort.
Right now I believe sendmail allows you to specify an alternate smarthost
that is used if there is no connection possible to the destination MTA. It
might be nice to let the alternate be used if the connection is rejected
by the MTA as a possible spamhost. That way you could send mail directly
to MTAs that accepted it, but divert mail to your ISPs smarthost for
destinations that required it. I don't think any MTA does anything
like this, though. It is a feature I would enable on our MTA, even though
we have never been on any DNSBL, as it would provide some insurance
against rejections should we land on one.
Daniel Feenberg
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