TECO isn't actually that bad, and I'd argue that it's roughly on the level of vi in complexity. I learned it just for fun, and found it more powerful than vi. I

TECO isn't actually that bad, and I'd argue that it's roughly on the level of vi in complexity. I learned it just for fun, and found it more powerful than vi. I was using videoteco when I learned it, and I recommend it to anyone that also wants to play around with this. I definitely would never want to go back to configuring sendmail though. Unlike TECO it doesn't provide anything compared to a modern mail product.