Everything Reggie does is on account of whether or not you allow it. Everytime Reggie jumps up, the behavior is reinforced. Dogs don't have an idea of good or bad behavior. Good behavior is whatever you make of it.

First, keep Reggie on lead. Have a friend ring the doorbell (your friend will be outside and you'll be inside). Let her bark, then tell her to be quiet. Ask for a sit and then treat/praise her. Take a couple steps back, ask for another sit and t/p. Have the visitor come in and if Reggie jumps up, walk backwards and get her attention. Ask for a sit, and then t/p. Allow the visitor to walk into the home, and ALWAYS have Reggie's attention. Now that the visitor is in your home, ask the visitor to make contact with Reggie if they want to. Ask the visitor to leave, and release Reggie from her sit.

What you're teaching is this: Reggie is not allowed to jump on visitors anymore. Reggie is not allowed to initiate contact with the visitor. That is the human's decision, not hers. It'd be a good idea to teach "Watch Me" or "Focus" before doing this.