We need to get beyond mechansisms that rely on listing
dialup blocks etc. There is simply too much hassle involved
getting blocks listed and unlisted etc. Blacklists are
not a cheap solution, maintaining them properly is very
expensive. What happens when someone is assigned an IP
block that has previously been identified as dialup?
how do they even know the listing exists? Similar problems
are being seen with the listing of IP blocks that were
previously 'unassigned' and hijacked by spamers, now
people are being assigned new IP blocks and finding that
they are blacklisted before they ever send a mail.
Our home DSL connection has been blacklistsed for a few years now, along
with other DSL networks the territory. Personally, given the cheap cost of
such connections and the high penetration of such connections in the local
community, I think that this is most likely a good thing. It was pretty
simple to for us to determine this - when we originally configured our mail
servers we got mail back saying we were denied because of the IP address
which we originated from. It is a common problem here unfortunately.
We have gotten around this problem here and on other networks in other
countries by employing a combination of BSMTP for inbound and authenticated
SMTP for outbound mail to our head office, effectively tunneling through the
ISP. But that can be problematic as some ISP's are now also blocking
OUTBOUND smtp from their dialup/DSL pools. I suspect that these numbers
will rise as more get clued into trying to combat the spam problems
originating from their networks. To add insult to injury, at least in this
part of the world (Asia), getting connected with an ISP that provides
reliable IP *AND* provides a reliable mail relay can be a daunting task.
What you bring up is a significant problem that needs to be addressed. I'm
not convinced that this is the right place for it however. On the other
hand, it would not be the first time I was wrong... :-)
postmaster(_at_)IPaddress is never guaranteed to work. We move
machines arround all the time. This email could go out
via any one of a number of email servers that are hosted
in completely different IP address blocks.
Exactly!
Best Regards,
-- Tim
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