Paul Vixie wrote:
mjc@cooper.org.uk (Martin Cooper) writes:
OK - but unconditionally permitting null-return paths means that spammers can drive a coach and horses through the hole it leaves. :-(
that's how the proposal is optional. spammers who lie about their source/return addresses using nonexistent domain names are not the subject of http://www.vix.com/~vixie/mailfrom.txt; rather, i'm trying to address the issue of spammers who lie about _existing_ source/return domain names.
This indeed will fix a lot of problems, and force people to use their "mail upstreams" mail-relays. ISP's should actually block port 25 outgoing, or even better, reroute/forward it to their own mail relay. This will force people to use their upstreams email address though when sending email outbound. And this isn't always what someone wants. But because especially the big U has many 'users' who simply take a dailup account, spew spam to all kinds of taiwanese, chinese, etc servers those 'users' aren't hard to block out unfortunatly. IMHO, Paul's idea is quite a good one, but all servers will need to be upgraded, and all dns entries installed. Unfortunatly that will take some time, installing a tool like spamassasin/razor etc is much more effective even though those tools won't stop spammers. At least it will help a bit against one of the bigger internet "problems". Greets, Jeroen