mh-insert-x-mailer-flag

mh-insert-x-mailer-flag is a variable defined in `mh-e.el'.
Its value is

t

Documentation:
*Non-nil means append an "X-Mailer:" header field to the header.

This header field includes the version of MH-E and Emacs that you
are using. If you don't want to participate in our marketing, you
can turn this option off.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 7.0 of the MH-E package that is part of Emacs 22.1.