To forward a message in mutt including all it's attachments, you can set the 
variable `mime_forward` as follows:

`set mime_forward`
`set mime_forward_rest=yes`

This however forwards all headers, attachments etc as
a single attachment.

A similar approach happens if you type `b`. This bounces the message completely
unmodified to a new address.
However, using the above two methods there is no way to trim the message.

Instead you can try:

1. 	type `v` to get to the attachments screen, and then type `t` repeatedly
	to tag the required attachments and then type `;f` to forward the tagged
	attachments.
2. 	Use the template method - type `Esc e` to resend the message using the
	current message as a template.