>Allow the client to lowercase (initially, or as a fallback) - I think >everybody agrees there is no harm in this *in practice*, then encode >with split base32. ...
No, for two reasons. One is that RFC 5321 clearly says that case folding is forbidden, and the mail world is very big. Every time I've assumed, that regardless of what the spec says, nobody does something any more, it turns out that someone still does, usually for a perfectly sensible reason that hadn't occurred to me. It is painfully evident that few people in this discussion have any experience with mail systems other than their own, and none with large (millions of mailboxes), and generalizing from limited experience is never a good idea. Also, to point out the obvious, this is just guessing that the mailbox associated with BOB@blah is the same one as bob@blah. Once again, it's putting a ten ton steel door on a cardboard box, as we too often do, which is just bizarre for a spec that is intended to be about security. The other reason is EAI. Billions of people write their names in UTF-8, not in ASCII, and they are going to have EAI mailboxes with UTF-8 names. You cannot case fold UTF-8 unless you know what language the name is written in, and often not unless you also know what sub-version of the language, e.g., the rules for Canadian French are different from the ones for French, Belgian, or Swiss French, and often not even then. There's stuff like traditional and simplified Chinese characters which are equivalent except when they aren't, and which is the canonical version is a highly political question. As should be obvious, I think that trying to force mailbox names into the DNS is a fundamentally bad idea, but the least bad way to do it is a base32 encoding of the exact name to be looked up since, unlike the other options, it at least allows for the possibility of a correct implementation. R's, John _______________________________________________ dane mailing list [email protected] https://www.ietf.org/mailman/listinfo/dane
