%% You should probably cite draft-ietf-sieve-vacation instead of this I-D.
@techreport{showalter-sieve-vacation-06,
    number =    {draft-showalter-sieve-vacation-06},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-showalter-sieve-vacation/06/},
    author =    {Tim Showalter},
    title =     {{Sieve: Vacation Extension}},
    pagetotal = 9,
    year =      2004,
    month =     aug,
    day =       24,
    abstract =  {This document describes an extension to the Sieve mail filtering language for an autoresponder similar to that of the Unix 'vacation' command for replying to messages with certain safety features to prevent problems.},
}