I used to use Trojita on a previous life where KDE was my main DE. But I notice that the software is not really maintained and it suffers from several lacks as encryped password support.

I don't see the point to have a lot of email clients, Geary, Claws Mails, Thunderbird, N1 and Evolution are already available on Solus.

That's just an user statement :)

As for encrypted passwords, I know Thunderbird doesn't support that, and iirc Geary doesn't either. I don't know about any of the others though.
I can certainly understand where you'd get the impression that Trojita isn't well maintained, since the interface could certainly use some work. However, Trojita is under almost constant development, with several patches a week.
KDE git
github "pulse"