appointments+ - newsletter checkbox - user added automatically to mailing list

I've got a question:
I added a checkbox to the confirmation box of the appointments+ plugin (when a user applies for an appointment) to check if the user would like to receive our newsletter. I would like to use a newsletter plugin and add the user automatically to a mailing list, when box is checked. would this be possible and if so - how? :slight_smile: I am not so firm in php or ajax coding but maybe you have an idea as how to get the information across to another plugin... TIA!