Assuming you mean that you don't want users to start a thread, have it answers and to then delete the thread, the simplest solution would be to not allow the Delete thread by self permission.
Thanks for your help but actually my point is about individual posts, not threads.
I have users who post some messages into for example very big and active threads, get answers, and then delete their messages.
Thanks for your help but actually my point is about individual posts, not threads.
I have users who post some messages into for example very big and active threads, get answers, and then delete their messages.