apparently-from
apparently-to
application
+application/postscript
application/pgp-encrypted
application/pgp-signature
application/pkcs7-signature
content-type
copiousoutput
date
+delivered-to
delivery-status
digest
edit
pgp-signed
pkcs7-mime
plain
+postscript
print
quoted-printable
received
supersedes
test
text
+text/plain
to
unknown
us-ascii