Private messaging

• UddeIM (separate free PMS extension, see template integration info here)
• Comments Cobalt Core (AFAIK, they can be private between Author and Commenter)

You are right Comments Cobalt Core has has the option for private comments although it has to be selected.

Making a testing on this I have selected that author of article can see private comments, article author has notification about a comment but he cannot see the comment.

Comments Cobalt Core has has the option for private comments although it has to be selected.

I see. Maybe a good option and feature request to make it a "default". I mean, in addition to mark it private on each new comment.

Comments Cobalt Core has has the option for private comments although it has to be selected.

author has notification about a comment but he cannot see the comment

Yes, exactly what I had in my mind. Your settings look good, IMHO. I would expect to see the comment. (might be a bug? I have not tested it myself, yet)

Comments Cobalt Core has has the option for private comments although it has to be selected.

Created an idea/request topic over here...

EDIT: Modified outdated AngelDesk link to correct Cobalt Forum topic ;-)