%% You should probably cite rfc3974 instead of this I-D.
@techreport{motonori-dualstack-smtp-requirement-01,
    number =    {draft-motonori-dualstack-smtp-requirement-01},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-motonori-dualstack-smtp-requirement/01/},
    author =    {Motonori Nakamura and Jun-ichiro Itoh},
    title =     {{SMTP Operational Experience in Mixed IPv4/v6 Environments}},
    pagetotal = 10,
    year =      2004,
    month =     may,
    day =       11,
    abstract =  {This document discusses SMTP operational experiences in IPv4/v6 dual stack environments. As IPv6-capable SMTP servers are deployed, it has become apparent that certain configurations of MX records are necessary for stable dual-stack (IPv4 and IPv6) SMTP operation. This document clarifies the existing problems in the transition period between IPv4 SMTP and IPv6 SMTP. It also defines operational requirements for stable IPv4/v6 SMTP operation. This document does not define any new protocol. This memo provides information for the Internet community.},
}