mh-reply-default-reply-to

mh-reply-default-reply-to is a variable defined in `mh-e.el'.
Its value is

nil

Documentation:
*Sets the person or persons to whom a reply will be sent.

This option is set to "Prompt" by default so that you are
prompted for the recipient of a reply. If you find that most of
the time that you specify "cc" when you reply to a message, set
this option to "cc". Other choices include "from", "to", or
"all". You can always edit the recipients in the draft.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 6.0 of the MH-E package that is part of Emacs 22.1.