attachments menu: macros

[Raphael Finkel <raphael@xxxxxxxxxx>]

I often get PDF attachments that are mis-labeled.  I use ^E in the
attachments menu and replace the mime type, and all is well.  I would
like to add a macro to the attachments menu to do that for me in a more
automatic way.  But I can't; mutt doesn't accept 

        :macro attachments ....

I am using Mutt 1.4.2.1i.

Raphael