Hello,
I am an administrator of a Discourse forum, and I have been asked whether it is possible to enable encryption for private messages. I noticed that the Discourse Encrypt plugin is obsolete. Is there a solution available?
Thank you very much for your help. 
The closest option right now is the site setting mentioned in this topic, which prevents admins from reading PMs by clicking a link in the interface. But of course, that is not the same as encryption. The messages can still be accessed by disabling the setting or by reading them in the database, for example, with Data Explorer.
There is a reason why Discourse calls them personal messages instead of private messages.
Thank you very much for your reply.
I believe it is this one:
Just to make sure I understand correctly: if I enable this and then create a private category, will I no longer see it in “All categories” and therefore be unable to modify its settings, unless I disable this option?
Thank you very much.
Hello,
I have another question: can you see when an administrator has viewed personal messages that were not intended for them?
Thank you very much,
Hi! 
For admins only: you can enable the Log personal messages views setting, which is disabled by default.
Besides this, the view count of the personal message increases for each new view, which might give a clue to the regular users that additional people have read it.
I just enabled it.
It says:
Display direct message views by an administrator for other users and groups.
I’m sorry, I didn’t quite understand. If an administrator viewed a direct message that wasn’t intended for them, where do the people in that direct message see it?
The description I see is
Log personal message views by Admin for other users/groups.
I thought it only created entries in /admin/logs/staff_action_logs but the description is ambiguous, so I’m not sure what it does besides that after all 
I still maintain that making personal messages private is something to consider again.