Your tutorials advise variably that I can…
1.use UE to create the necessary content on that page
2.must create the necessary form elements first than apply UE
So which is it?
both, you can do it either way.
if you are going to send a graphic represetation of the flier, create new static html page.
Add an image tag to it and add the full HTTP address to the image.
Then in UE Check the Create File For My Email Message and select the static html page you created.
as for what is sent when the client clicks send, in your case, the static html file is sent as the email.