RFC 4282 defined label = let-dig *(ldh-str) which means a single-label Unicode string would be absolutely fine since it translate to xn--gibberish. A shorter gibberish of cos, but still longer than a single character. -James Seng > Potential problems with global use of single-label names go beyond SMTP. > For example, RFC 4282, which defines the Network Access Identifier > (NAI), does not permit the use of single-label names. From Section 2.1: > > realm = 1*( label "." ) label > > As a result, someone purchasing the "example" TLD and using the NAI > bob@example in order to obtain access to the network, might well > discover that this would not work. > > > > > _______________________________________________ > Ietf mailing list > Ietf@xxxxxxxx > https://www.ietf.org/mailman/listinfo/ietf > > _______________________________________________ Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf