mh-clean-message-header-flag

mh-clean-message-header-flag is a variable defined in `mh-e.el'.
Its value is

t

Documentation:
*Non-nil means remove extraneous header fields.

See also `mh-invisible-header-fields-default' and
`mh-invisible-header-fields'.

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.