Mail: Load images manually when reading a message

[thierry8p]

I prefer NOT to load images in mail. For SPAM reasons.
So I set Load Remote Images to off.
But of course, very often I need to load the images I trust.

In the User Guide > settings > mail, I read "If Load Remote Images is off, you can load images manually when reading a message."

But I cannot find the way to do it. I looked everywhere

Would have liked to simply click on a hidden image and asked if I wanted to
-load the image
-load the images for this mail
-always load all images for this sender
-go to link
-cancel

Is there anything I am missing?
Thanks