%% You should probably cite draft-ietf-dane-smtp instead of this I-D.
@techreport{fanf-dane-smtp-03,
    number =    {draft-fanf-dane-smtp-03},
    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/03/},
    author =    {Tony Finch},
    title =     {{Secure SMTP with TLS, DNSSEC and TLSA records.}},
    pagetotal = 14,
    year =      2012,
    month =     jun,
    day =       6,
    abstract =  {SMTP has a STARTTLS extension, but (especially in the case of inter- domain mail transfer) it only provides very limited security because it does not specify how to authenticate the server's certificate. This memo specifies how TLSA records in the DNS can be used for proper SMTP server authentication.},
}