Am 11.09.2008 um 20:28 schrieb roger@mgz.ch:
great idea, whitelisting every system on the world which sends confirmation email .. it will be an big efford for that small country to convince the rest of the world ;-)
To be precise: I use dnsbl.sorbs.net to blacklist all dynamic IPs (and the RBL from spamcop, and also the swinog RBL - I would use spamhaus, but they blocked us because we make too many requests and we can't afford their prices). Then, I use the list on the SWINOG-RBL homepage to whilelist all the swiss dynamic IPs (and some other big systems, plus various IPs clients requested us to whitelist over the years) - because those are the one's that may actually want to relay through our system or send us mail legitimately. senderbase.org helps finding IPs of outbound relays, too.
I don't use greylisting - IMO, it's a system that doesn't work large- scale, in a similar way TMDA or other "please reply to this email or click on this link"-systems don't work in practise.
To be vaguely on topic - most of our customers have static IPs, and it's not a problem to set the PTR to another value. But we also don't boast 100000+ customers, like www.green.ch does - maybe they're afraid of having to change 100k PTRs, if they set a precedent? ;-)
IT would be so easy - it's just users and customers that make it difficult :-)))
Rainer