Kontact from the #KDE suite is a great email client. I haven't tried it yet for Windows because I am busy playing Kmines, Kblocks, Kapman, Ksudoku, Kbounce, Kolf, Kmahjongg and Kbreakout 😀 But I swear it's doing everything right.
(I also have an older build of Kpatience, but unfortunately, it's not included in this repository.)
So I tried Kontact's Kmail on Windows and managed to run it after a couple of hiccups and a system restart:
* Avast quarantined a bunch of EXE files to check them for viruses (all checks passed)
* Windows' Dark mode was a problem when adding a new email account (had to set Windows to Light mode)
* You better use KWallet, or it's pointless
* Had to manually set IMAP and SMTP
* Had to manually tick the checkmark on INBOX in IMAP->Advanced->Serverside Subscription to finally pull it's contents
Petar Toushkov