Project Responsible Field
I'll try to explain the feature with my real life example.
One day person came and asked me to create a project for him, so I duplicated a template for him and all fine. The problem is: now when I click in "My Page", it shows to me the issues related to that project which I don't care and I also used to receive e-mails from it (not sure if the e-mail is still being sent after Redmine 4).
So, what I imagine, is a simple way on the settings of selecting another person to be the responsible one, maybe a checkbox similar to adding member to a project. I imagine that this information is stored somewhere.