A very mighty, graphical emailclient
TkRat is a very nice e-mail client with a graphical user interface. It
supports all major protocols (SMTP, POP3, IMAP) and mailbox formats. It
has powerful search function, is localized, can handle encrypted and
MIME-encoded e-mail, has a nice mail monitor, can sync e-mail for
offline work, and has many other nice features.
There is no official package available for openSUSE Leap 15.4