Hi partner,
1. As far as I know, there is no way to achieve it without a template.
Using workflow or Power Automate can achieve this effect, but its complexity is no less than using an email template.
2. We can insert images from web resources into email template body.
For example, we can copy and paste the images in this thread directly into the template.


For system email templates, we can upload images to the web resources of the solution, and then copy and paste these images into templates body.
