Need upgrade our current mail server script (turn on built it PGP encryption by default, and design improvements)

Hello need update our current mail server script https://www.rainloop.net/, it actually have PGP end-to-end encryption includded but currently for regular user its not easy to use, so need make it allways turned on and encrypting/decripting automatical. And need add some visual improvements, mostly for mobile version which looks like total crap now. And also for desktop version need create nice looking dark theme which not exist now. And custom login page background picture option.

OR if you have better idea, like use some other as example tutanota open source script we are ready to move to it.