After "Each entry in the DNSxL MUST have an A record.", add "The A record MUST NOT be interpreted as an IPv4 address. It is an opaque value, whose presence simply means that the name or address queried is actually listed in the DNSxL."
Seems reasonable.
No, it's just experience. The last funny case is inside France Telecom (French largest ISP) where one mail server refused another one because it was blacklisted :-)
Orange/Wanadoo/FT has a dreadful spam problem, so bad that I've locally had blacklist about half of their outbound mail servers. If the point of the blacklist entry in question was to keep spam out of recipients' mailboxes, it was probably doing what it was supposed to.
Regards, John Levine, johnl@xxxxxxxx, Primary Perpetrator of "The Internet for Dummies", Information Superhighwayman wanna-be, http://www.johnlevine.com, ex-Mayor "More Wiener schnitzel, please", said Tom, revealingly. _______________________________________________ Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf