I would like to know what people use for handling email, as I've been using mutt for so long I don't really know what other folks do.
It depends on my platform.
On my daily driver (currenly Debian Stable; slated to become FreeBSD in the near future), I tend to use Claws mail but have been (sloooowly) transitioning over to mutt/neomutt.
For most of the other boxes that I manage, it's either mutt/neomutt for anything that requires real mail management, or mail(1) for those where I just need to read system messages and delete them without replying.
Here on tilde, I've given myself the challenge of using only mail(1) as my mail interface (including to compose this) and ed(1) as my $EDITOR.
It's been a great way to sharpen those skills.
That way I'll have an idea of what config examples to include on the docs or that perhaps there's no interest at all in this and I can use my time on other stuff ...
I'll grant I'm a bit of an outlier with mail(1), but the other two are pretty common based on the other replies I've seen here.