mh-compose-forward-as-mime-flag

mh-compose-forward-as-mime-flag is a variable defined in `mh-e.el'.
Its value is

t

Documentation:
*Non-nil means that messages are forwarded as attachments.

By default, this option is on which means that the forwarded
messages are included as attachments. If you would prefer to
forward your messages verbatim (as text, inline), then turn off
this option. Forwarding messages verbatim works well for short,
textual messages, but your recipient won't be able to view any
non-textual attachments that were in the forwarded message. Be
aware that if you have "forw: -mime" in your MH profile, then
forwarded messages will always be included as attachments
regardless of the settings of this option.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 8.0 of the MH-E package that is part of Emacs 22.1.