I know, you think your email pitches look better if you put big, fancy graphics in them. But they don’t look so hot if your recipient has images blocked by default, or worse, is reading their messages on a smartphone with a slow data link. Or even worse, on an airplane with no connectivity.
Do you want your message to be pretty, or do want it to be read?
At the very least, put the actual content of the message in text up at the top of the message. That way, your recipient can read it regardless. Also, it’s much easier to copy and paste information from an email into a calendar or to-do list if there’s actual text to select.