My friend Paul Wolberg forwarded this one: if you're a spammer and you want to avoid algorithmic or signature detection, you can't use words. But if you use images, many mail readers won't display them. Thus:
When I arrived at Michigan State in 1974, one of my first trips was to the Computer Center, where I encountered Dr. Charles Wrigley, who gave me an account on the Control Data 6500 mainframe. One of the first cool apps I encountered allowed you to print banners with ASCII characters as the pixels. I remember printing out my first letter back home using it.
The command was hal,banner as I recall.
Plus Ça Change