GUIs are overrated
I'm in the process of migrating to a new PC at the moment and for email I have Claws mail operational like it has been for decades. What surprised me though is how much I miss mutt, which I've used for my main email account for ages (though not nearly as long as Sylpheed/Claws.)
I have been using mutt for a few years with isync and notmuch to create an indexed local repository of my email (which is otherwise accessed via IMAP) - maybe it's just me, but I find even using a lean and decent GUI email client is far more cumbersome than using mutt. The only fly in the ointment is HTML-only emails, which while they can be handled tolerably well add a definite layer of inconvenience.
I genuinely found it surprising just how much I missed that CLI based workflow, even though it's only temporarily...