when you open the files in mac, do you open them in web browser or something?
anyways, what you can do is write up an html page with all the extras linked (or embedded) to the page
zip them together, and send them thru mail
then ask your friend to unzip and open them in their web browser
another way (correct me if i'm wrong, but i think this is the way most html emails are sent) is to have the extras and embedded files stored in the server somewhere, and the html page link to them using absolute URL. that way when the email is opened, it's like opening a website where you store the page, etc....
i think if you convert your file to power point slide (provided that you have msword), you can embed everything and even have audio files to autoplay ... haven't really tried it yet, but worth it, perhaps?
good luck
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