I’ve been using djbdns and qmail for many years, specifically because after reviewing its code and comparing it to other possible alternatives, I objectively decided that these two pieces of software are superior in all aspects.
Lots of people have cast aspersions on D. J. Bernstein and his software, usually with emotional and irrational claims. Of course, most of these people can’t even read code well enough to understand what it does or how it does it. However, when you encounter the opinions of actual programmers, we all tend to share a similar but different opinion.
Today, Aaron Swartz put this into words better than I could: D. J. Bernstein is the greatest programmer in the history of the world. The money quote: