Can't the PM have some end to end encryption? Like WhatsApp and other message software?
You could still rely on those third party servers to send the encrypted messages, but they would be encrypted, so nobody would be able to read them. Why cant this be implemented?
I would support adding something like that.
Not long ago one forum member released browser based project, and that could also deliver some kind of encrypted communication between forum members.
However, I don't think making something similar directly with forum code won't be that easy, but I could be wrong.