How to activate the pop up private message?
 

Ok i am tired sending to my each new Registered members that they have to post in this section able for them to use the site, that's why i made the Automatic pm received for my newly registered members. but the problem is they dont open it after they signed up. maybe because they dont see it and they dont know that hey have a pm from me.

So i want to activate my Pop-up private message turn on for all my NEW registered members and have them edit it after if they still want this on or not in their User CP.

So can anyone here tell me how to activate this features? thanks in advance guys