On Fri, 26 Sep 2003, Brian Gibbons wrote:
From: "Simon Byrnand"
[half hearted effort to block spam] (And in that category I include manual blocking of huge swarths of ip space, outright blocking based on most RBL blacklists, Mailmarshall, and Challenge response systems, all of which have unacceptable collateral damage
Well said.
I recently dealt with an ISP in the US who had blocked 202.0.0.0/8 (!) because "all we ever get from that netblock is spam from China".
And there is the issue.
If ISPs use network blocking as a mechanism to block Spam then the ultimate outcome will be be a block on all networks and zero email delivery.
A human being can scan down 20 emails in their Inbox and immediately descriminate between Spam and valid email because they have an educated eye and brain.
My comment on this is simply that I do not block at the /8 - I use whois, and DNS, and calculate exactly how wide a block I can put in without blocking someone *elses* network.. and I do that. If I cant do it by network then I do it by /32, starting with the offending MTA. I don't agree with blocks such as 202/8 (been the victim of one of those) but I think educated, selective blocking is quite acceptable - at least untill those networks involved actually do something about the whole 'spam' thing. What amazes me is the number of people out there who still thing opt-out is acceptable.. Mark.