Send Custom Email Option

The "Send Custom Email" option on "Tasks" and "Submit Rules" needs an "email field" option for the "sender". I want the emails to automatically go to senders that are controlling the app that I made. I do not want to be forced to be put in one email address because it will not be connected to the specific company controlling the app. Also, I want certain emails to go to certain senders.

It would be great if the "sender" email field could have a connection to a drop down to specific users in addition to user roles.