7bit
8bit
alternative
apparently-from
apparently-to
application
audio
base64
bcc
binary
cc
compose
composetyped
content-description
content-disposition
content-length
content-transfer-encoding
content-type
copiousoutput
date
digest
edit
expires
external-body
followup-to
from
image
in-reply-to
iso-2022-jp
lines
list-post
mail-followup-to
mail-reply-to
message
message-id
mime-version
model
multipart
nametemplate
needsterminal
news
newsgroups
organization
print
quoted-printable
received
references
reply-to
return-path
rfc822
sender
status
subject
supercedes
supersedes
test
text
to
unknown
us-ascii
utf-8
video
x-comment-to
x-convert
x-label
xref
x-status
x-uuencode