on Tue, Sep 08, 2009 at 09:57:58AM -0500, Tom Pipes wrote:
[...] We have done our best to ensure these blocks conform to RFC standards, including the proper use of reverse DNS pointers.
Sorry to jump in so late, been catching up from vacation. I'm checking out the PTRs for the /18 you mention, and I see that you've used a few different naming conventions, some of which are friendly to those who block on dot-separated substrings, some of which are confusing, and some of which are custom to specific clients. If I could speak on behalf of the tens of thousands of mail admins out there for a minute, I'd ask that instead of (e.g.) 69.197.115.62: 69-197-115-62-dynamic.t6b.com you instead use a dot to separate the 'dynamic' from the generated IP-based hostname part, a la 69.197.115.62: 69-197-115-62.dynamic.t6b.com This allows admins of most FOSS MTAs to simply deny traffic from all of those hosts on the grounds that they are dynamically assigned, for example in sendmail's access.db: Connect:dynamic.t6b.com ERROR:5.7.1:"550 Go away, dynamic user." If you choose not to, it doesn't bother me; I've got a rather extensive set of regular expressions that can handle those naming conventions, but the rest of the mail admins may find it more friendly were you to do so. Additionally, it may also be useful to indicate what sort of access is being provided, so for dialups you might want to do 69.197.115.62: 69-197-115-62.dialup.dynamic.t6b.com (Note: not 'dynamic.dialup.t6b.com', most people care more about whether a host is dynamic at least in the context of antispam operations). I also note that the vast majority of the /18 simply lacks PTRs at all; you also mix statics and dynamics (though on different /24s, eg 69.197.106, 69.197.107, 69.197.108 seem static where 69.197.110, 69.197.111, and 69.197.115 do not, with more statics seen in 69.197.117 and 69.197.118 ff.) and don't seem to SWIP the statics or indicate in whois which are dynamic pools. All of these are likely to result in unfunny errors by DNSBL operators if they decide that you're serious and the whole /18 is dynamic based on a preponderance of hosts in some /24s with dynamic-appearing names AND a lack of evidence otherwise in the whois record. Of course, if you follow MAAWG's port 25 blocking BCP, it's moot as far as the dynamics go. Ultimately, you'd want to make sure any static customer intending to provide mail services have their own custom PTR(s) for those hosts, in their domains (not yours). HTH, Steve -- hesketh.com/inc. v: +1(919)834-2552 f: +1(919)834-2553 w: http://hesketh.com/ antispam news and intelligence to help you stop spam: http://enemieslist.com/