While this is an interesting discussion, I think that when the OP said
a "header", he meant a brief statement at the top of the email body
serving as a preface to the real content, not an RFC-style "header".
Sorry for my last double reply, there was a glitch in Gmail saying that the first message was not sent due to a server error or temporary caching desynchronization (and then the interface blocking on attempt to synchronize). But apparently it was still sent correctly, as I see after forcing the complete reload of its web interface...
