I was about to ask the mutt-users mailing list a question, when it occurred to me that I should really google it first. Indeed, my question had been answered about 3 years previously. And it’s really useful.

mutt is a mail user agent, like Thunderbird or GMail. Unlike GMail, it is not tied to a specific mail service, and unlike Thunderbird, mutt does not have a graphical point-and-click interface. mutt runs inside a terminal (like xterm, iterm or just about anything that you can use ssh in).