On Tue, 16 Sep 2003, Dean Anderson wrote: > On Tue, 16 Sep 2003, Bruce Campbell wrote: > > > On Tue, 16 Sep 2003, Edward Lewis wrote: > > > > For these items of software to change from using a stateless method of > > existence-verification with low overhead, to using a semi-stateless method > > of existence-verification with high overhead, is something akin to the Y2K > > bug in scope, albeit without all the hype. > > The correct way to check for "domain existance" for email is to lookup an > MX record. That would be the correct method as defined in RFC2821 would it? The one which specifies: 5. Address Resolution and Mail Handling If no MX records are found, but an A RR is found, the A RR is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host. > > Operationally, having one's not-low-overhead whois server being hit by > > automated queries solely for existence-verification is a terrible state of > > affairs. > > One shouldn't be doing whois queries. One just wants to know if the domain > of the sender can receive email, back. Yes. If I receive an SMTP connection purporting to be from 'joebloe@ssdflvndslkvn.com', and I follow the established standards for seeing whether I can send mail back, I end up with 64.94.110.11 . Ergo, as far as that domain is concerned, it can receive mail back. ( This was covered at least 40 messages ago, do try to keep up ). --==-- Bruce.