message-ignored-resent-headers

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

"^Return-receipt\\|^X-Gnus\\|^Gnus-Warning:\\|^>?From \\|^Delivered-To:\\|^X-Content-Length:\\|^X-UIDL:"

Documentation:
*All headers that match this regexp will be deleted when resending a message.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.