ProtonMail enables you to load the images in the messages you receive automatically or manually. Here you can learn about the difference between both settings and how to change them.
When receiving a message with an image in it, ProtonMail will prompt you to manually select Show Images by default. This is implemented to improve the security of your account by ensuring no code is executed on your system without your knowledge.
By selecting Show Images ProtonMail will display all images that are embedded in the message through an external link.
You can make embedded images display automatically by visiting your Settings, within the Account tab of settings you will find Email Images toward the bottom of the page. Select Auto to have all links executed automatically.
Please note: the Show Images feature only applies to images that are embedded in a message through an external link. If the image is stored in the message directly, it will be displayed as an attachment at the bottom of the message. If you are not seeing images in a message that you were expecting to see, please check the attachments of the message.