%% You should probably cite draft-ietf-marf-not-spam-feedback instead of this I-D.
@techreport{li-marf-not-spam-feedback-00,
    number =    {draft-li-marf-not-spam-feedback-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-li-marf-not-spam-feedback/00/},
    author =    {Kepeng Li and Barry Leiba},
    title =     {{Email Feedback Report Type Value : not-spam}},
    pagetotal = 7,
    year =      2011,
    month =     may,
    day =       13,
    abstract =  {This document defines a new Abuse Reporting Format (ARF) feedback report type value: "not-spam". It can be used to indicate that a message that was tagged or categorized as spam (such as by an ISP) in fact is not spam.},
}