%% You should probably cite draft-ietf-dane-smtp instead of this I-D.
@techreport{fanf-dane-smtp-01,
    number =    {draft-fanf-dane-smtp-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-fanf-dane-smtp/01/},
    author =    {Tony Finch},
    title =     {{Secure inter-domain SMTP with TLS, DNSSEC and TLSA records.}},
    pagetotal = 11,
    year =      2012,
    month =     may,
    day =       29,
    abstract =  {SMTP supports STARTTLS for inter-domain mail transfer, but it only provides very limited security because the server's certificate cannot be authenticated. This memo specifies how TLSA records in the DNS can be used for proper MX target server authentication.},
}