Command line email. Written in C programming language. Developed at the University of Washington. Very nice to use.
I've been using this since it was "Pine" back in the 90's. Small, powerful, and easy to use remotely from a terminal.
I used to use this when email first came out, at times I'm tired of the web based email, plus this is a lot faster.
Absolutely love it, I use it on a daily basis. Great for text based email without the additional overhead. Easy to navigate if you know the Pico/Nano editors.