> > In IPv4, the absence of a PTR record was taken as a spam signal, > together with all the other spam signals; in IPv6, they decided to just > say "no". Which is stupid because many ISPs didn't run proper reverse for v6 and couldn't delegate to their customers. Which broke many small email servers Upon which the ISPs started auto generating PTR records. Upon which the anti spammers rejected auto generated PTR as valid and rebroke the small email servers. Upon which those mail systems just stopped using IPv6. Upon which we all lost