<li>S​/​MIME: Secure/Multipurpose Internet Mail Extensions (cf. <ahref="#RFC8551"class="xref">[RFC8551]</a>)</li>
<li>PGP/MIME: MIME Security with OpenPGP (cf. <ahref="#RFC3156"class="xref">[RFC3156]</a>)</li>
<li>Message: An Email Message consisting of header fields (collectively called “the Header Section of the message”) followed, optionally, by a Body; cf. <ahref="#RFC5322"class="xref">[RFC5322]</a>.</li>
<li>Transport: The entity taking care of the transport of a Message towards the receiver or from the sender. The Transport on the sending side typically determines the destination recipients by reading the To, Cc and Bcc Header Header Fields (of the Outer Message). The Transport is typically implemented by an MTA (Mail Transfer Agent).</li>
<li>Transport: The entity taking care of the transport of a Message towards the receiver or from the sender. The Transport on the sending side typically determines the destination recipients by reading the To, Cc and Bcc Header Fields (of the Outer Message). The Transport is typically implemented by an MTA (Mail Transfer Agent).</li>
<li>Header Field (HF): cf. <ahref="#RFC5322"class="xref">[RFC5322]</a> Header Fields are lines beginning with a field name, followed by a colon (“:”), followed by a field body (value), and terminated by CRLF; cf. <ahref="#RFC5322"class="xref">[RFC5322]</a>. <br><br> Note: To avoid ambiguity, this document does not use the terms “Header” or “Headers” in isolation, but instead always uses “Header Field” to refer to the individual field and “Header Section” to refer to the entire collection; cf. <ahref="#RFC5322"class="xref">[RFC5322]</a>.</li>
<li>Header Section (HS): The Header Section is a sequence of lines of characters with special syntax as defined in <ahref="#RFC5322"class="xref">[RFC5322]</a>. It is the (top) section of a message containing the Header Fields.</li>
<li>Body: The Body is simply a sequence of characters that follows the Header Section and is separated from the Header Section by an empty line (i.e., a line with nothing preceding the CRLF); cf <ahref="#RFC5322"class="xref">[RFC5322]</a>. It is the (bottom) section of Message containing the payload of a Message. Typically, the Body consists of a (multipart) MIME <ahref="#RFC2045"class="xref">[RFC2045]</a> construct.</li>
@ -735,7 +735,7 @@
<pid="rfc.section.4.1.1.1.p.7">The impact of using “text/plain”, while in fact containing a (subset of a) “message/RFC822” media type to be parsed, is for further study concerning MIME standards and real world deployments.</p>
<pid="rfc.section.4.1.1.1.p.8">For further information, the reader is encouraged to consult <ahref="#I-D.autocrypt-lamps-protected-headers"class="xref">[I-D.autocrypt-lamps-protected-headers]</a>.</p>
<pid="rfc.section.4.1.2.p.1">It is RECOMMEND that the Inner Messages contains all the Header Fields of the Original Message with the exception of the following Header Field, which MUST NOT be included to the Inner Message nor to any other protected part of the message:</p>
