Credit card plug in or ....?

We want to charge the customer only when the delivery happens. I believe that is the legal requirement.

Is there a plug in that allows for this to happen.

1. Authorizes the amount during the sales on the website

2. Collects the payments when delivery is done

I looked at the www.citixsys.com solution but that is for the back end processing.

Your help is appreciated.

Mike