Memory Hole is a project to move mail headers into the encytped/signed part of the mail.
this a good thing from privacy, we should support this.
The basic idea is to have a mimelayout like this:
encrypted (after decryption):
multipart/encrypted: multipart/mixed text/rfc822-headers multipart/alternative text/plain text/html
and the text/rfc822-headers will have the encrypted ( and signed) approved headers of an mail like To,CC,BCC, Subject,References,...