%% You should probably cite rfc8461 instead of this I-D.
@techreport{ietf-uta-mta-sts-01,
    number =    {draft-ietf-uta-mta-sts-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-ietf-uta-mta-sts/01/},
    author =    {Daniel Margolis and Mark Risher and Nicolas Lidzborski and Binu Ramakrishnan and Alex Brotman and Janet Jones and Franck Martin and Klaus Umbach and Markus Laber},
    title =     {{SMTP MTA Strict Transport Security}},
    pagetotal = 17,
    year =      2016,
    month =     jul,
    day =       8,
    abstract =  {SMTP MTA-STS is a mechanism enabling mail service providers to declare their ability to receive TLS-secured connections, to declare particular methods for certificate validation, and to request that sending SMTP servers report upon and/or refuse to deliver messages that cannot be delivered securely.},
}