"I'd probably run it in a non-privileged container."

Does mutt talk to the network or have a daemon or run as a service ? I don't know the answer to that but I know that for my own use-case, pine is basically a text editor. It executes no programs or code and does not talk to anything but the local SMTP daemon.

How much sanity checking and bounds checking does sendmail (or postfix or whatever) do on email ? That's the question, I think, because again, in my case, the threat vector is very limited - basically an arbitrary (weird) email or piece of an email that somehow breaks pine.

So no, I don't run it in a container - in fact, I run it as the user whose mail spool is the highest sensitivity asset that user owns ... so a container wouldn't help. If you get the mail spool, you get everything - at least or that user...

When I used Alpine, it was talking to IMAP and definitely segfaulted a couple times. But an RCE in Alpine != RCE in Postfix (great architecture). I dunno MUAs are so personal, they feel like a perfect place to target and handle more edge cases than upstream processes.

The last commit to that git repo was a couple days ago, and looking at the log, it gets a new commit every week or so. It may be under different stewardship now, but it definitely seems maintained. The last stable release was last year, but development seems to be proceeding nicely. The full site is at http://alpine.x10host.com/alpine/.