Hello @boemerang.zah and sorry for the late reply.
Unfortunately, the send email block is only for sending text and not images
The only workaround I can think of is to use the share image block
But you will need to save the image as base64 and not the URL.
You can find more instructions on how to get images as base64 here:
WEB API Firebase Storage It does not upload the file to the server - Questions about Thunkable / Web API’s - Community
When I tested it it worked only on android.