Etach is an Emacs add-on that allows easy management of MIME email
attachments in RMAIL and Mail modes.  Attachments and detachments are
as simple as entering the Emacs commands M-x attach and M-x detach,
respectively.  Also provided is the ability to forward mail via
message/rfc822 format (M-x mime-forward), useful when forwarding
messages that contain MIME attachments.