Looks like using smtp it migh tnot be possible to display in gmail.check the below knowledge base…which has a note
Alternately…Try to open this old xaml may be you might find something useful…but chances are sleek using old methods…create html content is not available for you in older version…so as of now these are the options…else need to go with any coding …other than using UiPath activitiy directly
Also instead of giving a image in attachment try to use a online image and check if that works…give the url of image and see may be if that solves then we might see for different approach to save out images