Private messages: Ability to mark as unread

A lot of companies not only use personal moderator accounts but also create and use shared community accounts for community service purposes. As moderators can be absent (on sick leave, on vacation, etc.), pulling users into a 1-on-1 conversation is done with the shared accounts so no private messages get forgotten.

Because multiple people use the same account, it would make working easier if moderators could mark private messages as unread if they read it but don’t do anything about it at this point. This way the next moderator who is responsible for the shared account is less likely to miss a potential follow-up task.

The conversation partners (users) shouldn’t be able to see the read / unread status.