For Gmail users this will be a good news for you! I’ve just discovered today that you will be able to insert image on the body of your email – not just an attachment. But you are free to attached it as well.
First: Go to your Gmail “Settings“.
Second: Click on the “Lab” tab.
Third: Enable your “Inserting Images“, then after you save the changes you will see this on your compose box. (See picture below)