Never one to turn down a free bagel, I sent away for a coupon from my friendly neighborhood bagel shop. They e-mailed it, as promised, but without any regard for the way most e-mail programs by default disable images. Because the entire thing is an image, I couldn’t tell what arrived in my in-box, and I almost deleted it before recognizing the subject line.
Here’s what I was looking at:

What happens if you go picture-bonkers
The lesson? Use images judiciously in your outgoing messages. And always make sure you use ALT text in case pictures don’t display.