message-ignored-supersedes-headers

message-ignored-supersedes-headers is a variable defined in `message.el'.
Its value is

"^Path:\\|^Date\\|^NNTP-Posting-Host:\\|^Xref:\\|^Lines:\\|^Received:\\|^X-From-Line:\\|^X-Trace:\\|^X-ID:\\|^X-Complaints-To:\\|Return-Path:\\|^Supersedes:\\|^NNTP-Posting-Date:\\|^X-Trace:\\|^X-Complaints-To:\\|^Cancel-Lock:\\|^Cancel-Key:\\|^X-Hashcash:\\|^X-Payment:\\|^Approved:\\|^Injection-Date:\\|^Injection-Info:"

Documentation:
*Header lines matching this regexp will be deleted before posting.
It's best to delete old Path and Date headers before posting to avoid
any confusion.

You can customize this variable.