Using Elements in emails
What elements can be used in emails?
Link elements, which provide a URL that donors can go to and be redirected to your webpage of choice with the checkout or fundraiser setup form open, are usable in emails as you can just share that URL in the body of the email, either as a regular link or as a link on a faux-button (using an image or CSS styling).
QR code elements provide an image file that allows you to share the QR code anywhere. As such, you can use HTML in your emails to call in the QR code. Please do keep in mind though that QR codes are much easier to read off of paper or physical media than most LCD screens.