@misc{rfc1847,
    series =    {Request for Comments},
    number =    1847,
    howpublished =  {RFC 1847},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC1847},
    url =       {https://www.rfc-editor.org/info/rfc1847},
    author =    {Sandy Murphy and James Galvin and Steve Crocker and Ned Freed},
    title =     {{Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted}},
    pagetotal = 11,
    year =      1995,
    month =     oct,
    abstract =  {This document defines a framework within which security services may be applied to MIME body parts. {[}STANDARDS-TRACK{]} This memo defines a new Simple Mail Transfer Protocol (SMTP) {[}1{]} reply code, 521, which one may use to indicate that an Internet host does not accept incoming mail. This memo defines an Experimental Protocol for the Internet community. This memo defines an extension to the SMTP service whereby an interrupted SMTP transaction can be restarted at a later time without having to repeat all of the commands and message content sent prior to the interruption. This memo defines an Experimental Protocol for the Internet community.},
}