Sometimes the photo’s in my emails only download if I hit the reply button, & disappear again if I cancel reply. How can I fix it?

When receiving emails from a friend, empty outlines of the pictures sometimes appear instead with those little missing picture logos's in the middle. If I click  reply, they appear, but if I click cancel to go back to normal, they disappear again. Usually it doesn't happen the fist time I open it, but happens every time after.