Our recommendation to use PM inside our community is always to make sure the “GREEN” Encrypted icon in the message bar. 
This guide will show you how to do that in few steps.
Profile Security
Go to your profile preference, and follow below:
check the setting of your keys, and the encryption key pair.
Once you click, make sure to open your notepad, or save the backup codes in any external paper ( use these codes like your password ).
Manage Keys
Select Export Encryption Key Pair Then follow the screenshot below.
Export Keys
Now click on Generate Paper Key
Generate Paper key
Save the key (SEED) in external paper or in safe place.
Save backup key
Make sure to save the Encryption Key Pair since you need it in case of any damage or lost as a backup.
Encryption Enabled
Now you can see once you select a user to communicate or send private message a green key, which mean your message is encrypted and secure.
In case you want to delete the message from the reciever, you can select the time clock beside the green key, and select the period time.
Destroy Message
The site admin, staff, nobody can assist you if you lost these keys, also our recommended communication in out community is to use this way for communication between the community users.