Adding an icon to a gmail message using G suite add-on

Question

Is it possible to add an icon or banner to the gmail interface that will be shown on top of a email message?

If yes, how? I could not find any information about it in the G Suite developer guide.

Answer 1

You can do this without any extensions with Canned Responses. Go to settings > advanced to enable them, then composes a new message. Add your image, click the three-dot menu > Canned responses > Save draft as template > save as new template. In the future when you're composing a message you can load the template to place your image or banner there.

If you want to use HTML, you need to send mail with the Gmail API. The easiest way to do this is with App Script, the instructions are here . Keep in mind this means writing your entire email in a text editor.