x400

x-webtv

x-vms

x-uidl

x-ph

x-n2p

x-ms

x-mimeo

x-mime

x-mailer

x-list

x-envelope

x-char

user-agent

ua-

return

resent-message

references

precedence

p1-

original-encoded

mime-version

message

mail-system

list-software

in-reply

errors-to

disposition

delivery-

content-

received