Type: quadoption
Default: unset
When set, the message you are forwarding will be attached as a separate MIME part instead of included in the main body of the message. This is useful for forwarding MIME messages so the receiver can properly view the message as it was delivered to you. If you like to switch between MIME and not MIME from mail to mail, set this variable to ask-no or ask-yes.
Also see forward_decode and mime_forward_decode.