The UW no longer wanted to support Pine but they were unable to release it under the existing license. It was mostly rewritten as Alpine ( https://www.washington.edu/alpine/overview/story.html ), and is now sort of maintained by other folks: http://alpine.x10host.com/alpine/

I still use it regularly and it still works well, but I should probably be looking for something else.

Not at all similar, but mutt is a fantastic replacement. Like Vim, very powerful once you get in to it.

There was a fork/successor called alpine, I recall having to setup for my wife. But beyond that I think that mutt eventually "won". (Especially when development started picking up again with mutt-ng, etc.)

I wrote a console-based mail-client with lua-based scripting, over at https://lumail.org/ but I don't think I have more than 50 hard-core users. It seems like most people use mutt, and work around its annoyances, or use web-browser for their mail.

(I realize at some point notmuch came out and became popular, but I've never had a strong feeling for how popular. I think I'm a little biased since I read of people using it, but nobody "local" to me does.)

I was used to pine and pico so I migrated to alpine and nano. Alpine works fine for me, alpine is very much like pine. I have spamassassin tagging mail as spam, and I have an alpine filter that moves those tagged messages to a possible spam folder.

I was used to pine when mutt came out, so I always used pine or alpine. You can check both out and see which you prefer.

There's alpine, but I haven't use it yet, so can't say if it's as good ;)