HTML Emails convert to plain text on Forward/Reply

Using OS X 10.12.6, mail 10.3 client

Whenever I receive an HTML email, then try to forward it to someone else it converts it from HTML format to plain text, which causes the email to lose all its images. The person receiving it on the other end gets this horrible looking message with mile-long links that mean nothing to them and a useless message. When I use Outlook it keeps the HTML formatting when sending, but Mac Mail can't seem to do that.

How can I change this so Mac Mail will send the HTML email out so the recipient can actually figure out what the email is about?

See attached images to see what I'm talking about.

Thanks!