@techreport{levine-additional-registered-clauses-03,
    number =    {draft-levine-additional-registered-clauses-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-levine-additional-registered-clauses/03/},
    author =    {John R. Levine},
    title =     {{Update to Additional Registered Clauses in SMTP Received Headers}},
    pagetotal = 5,
    year =      2019,
    month =     jul,
    day =       30,
    abstract =  {SMTP servers add Received: trace headers to mail messages to track their progress This document updates the registration criteria for Additional Registered Clauses in those headers to Expert Review, and adds new clauses for Server Name Indication (SNI) and sending port number (PORT).},
}