%% You should probably cite rfc3656 instead of this I-D.
@techreport{siemborski-mupdate-04,
    number =    {draft-siemborski-mupdate-04},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-siemborski-mupdate/04/},
    author =    {Rob Siemborski},
    title =     {{The Mailbox Update (MUPDATE) Distributed Mailbox Database Protocol}},
    pagetotal = 19,
    year =      2003,
    month =     may,
    day =       15,
    abstract =  {As the demand for high-performance mail delivery agents increases, it becomes apparent that single-machine solutions are inadequate to the task, both because of capacity limits and that the failure of the single machine means a loss of mail delivery for all users. It is preferable to allow many machines to share the responsibility of mail delivery. The Mailbox Update (MUPDATE) protocol allows a group of Internet Message Access Protocol (IMAP) or Post Office Protocol - Version 3 (POP3) servers to function with a unified mailbox namespace. This document is intended to serve as a reference guide to that protocol.},
}