on Fri, Jul 09, 2021 at 09:25:57AM +0200, Hans-Martin Mosner via mailop wrote: > IMHP that's the wrong approach. The question isn't whether IP > addresses are dynamically or statically assigned, but whether it is > possible with reasonable effort to find an entity that is responsible > for SMTP traffic coming from an IP address. It doesn't matter whether > the IP address has no pointer, has "dynamicip" or "staticip" or one of > the various anonymous cloud hosting domain names in it.
I can assure you that the approach is valid. I don't know of anyone who still accepts mail from hosts without a PTR, period. And I do know for certain that many find distinguishing between generic, static, and dynamic (as well as several other classifications, such as shared or dedicated webhosts, residential university networks, NATs, etc.) extremely useful in the context of not just inbound SMTP but also a variety of other contexts where the nature of the source matters. Correlations are useful. Now, you're right in thinking that reaching a responsible party is an important aspect of making manual decisions as to who to block; with the devastation that is WHOIS and the GDRP that has become well-nigh impossible in many, if not most, cases, and the proliferation of idiocy that is the failure to provide a working abuse@ address for every domain and replacing them with alternates or even jump-through-hoops Web forms for reporting abuse isn't helping. It's a lot easier to set policy based on your tolerance for static/dynamic/generic/etc. and let the MTA or filter make the decisions for you using a dataset based on classified naming conventions. Why should that be any different than how you might use SPF or DKIM/DMARC? YMMV, your server, your rules. But I wouldn't have been able to collect and classify almost 275K naming patterns over the past 18 years, with a coverage of ~97% of the IPv4 PTR namespace, if someone didn't find the dataset valuable... Steve -- hesketh.com/inc. v: +1(919)834-2552 f: +1(919)834-2553 w: http://hesketh.com/ Internet security and antispam hostname intelligence: http://enemieslist.com/ _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
