I’ve been reading a lot about how email is broken these days—articles here, here and here are examples—and interestingly, I came across the following passage in Cryptonomicon (published in 1999) that I thought was apropos:

“I hate e-mail,” John says.

Harvard Li stares him in the eye for a while. “What do you mean?”

“The concept is good. The execution is poor. People don’t observe any security precautions. A message arrives claiming to be from Harvard Li, they believe it’s really from Harvard Li. But this message is just a pattern of magnetized spots on a spinning disk somewhere. Anyone could forge it.”