Pronestors email notifications contains pictures. They work better if you enable pictures from Pronestor.
This guide isn't made with a Pronestor notification email, but the process is the same.
Open your email
At the top there is a message
Click on "Click here to download pictures"
Click on "Add the Domain @notification.pronestor.com to Safe Sender List"
Your emails from Pronestor will now show pictures