Kind of a neat feature, if you click on User Menu from any one of the main forum pages and then click on Edit Your Profile, you can select an image to appear by your post. Ideally it's a small square image 48x48 pixels in size. Just as a test this message should have an image by it.

edit, I removed the image from my profile and then I checked the message and the image was gone. This thing is smart! Let's see if this brings it back.