RFC 1847: Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted
Defines MIME framework for signed and encrypted message parts, foundation for S/MIME and PGP/MIME.
MIME standards
RFC 2049: MIME Part Five: Conformance Criteria and Examples
Defines MIME conformance levels and provides worked examples for implementers.
RFC 2047: MIME Part Three: Message Header Extensions for Non-ASCII Text
Defines encoded-word syntax for non-ASCII characters in headers.
