I think the last MUA (Mail User Agent [what sysadmin sorts call email clients]) I enjoyed? Was elm.
Sure, I made use of pine. Arguably, I still think pico is one of the better TUI text editors (and the creation of nano, continues to confuse me).
I remember when thenewsh mentioned how Microsoft, broke Exchange's IMAP support with pine (the reference IMAP client). That was back when I used to get paid to administer an Exchange server from an employer (unfortunately, I would have other employers who also ran that awful MTA [Mail Transfer Agent, what we sysadmin sorts refer to email servers]). Of note: there is not a single employer I had, which ran Exchange, which did not also run other MTAs, in front of Exchange, as a matter of security, for antispam and such. Exchange has always been, and presumably will always be: the worst email server ever. Take that from someone who hates sendmail enough I usually referred to it as "sendwhale" as a pejorative. Take that from someone: who had a UUCP email address, before an SMTP address.
I concede, that mutt continued to make TUI MUAs, usable. Alas, IMHO, HTML in email was an antipattern, and I know whom to blame for it too; but that ship sailed and we're in the worse timeline now.
But, back in the day?
Using elm? Was still the apogee, for me at least.