It is very important to follow-up with your new and returning preferred customers. Here are some sample email from my drafts folder. Whenever I need to send one out, I just copy/paste the contents into the new email and customize as necessary. If you do copy these, you'll want to be sure to update all the links so that they point to your web portals and not mine.
Customer Welcome and Thank You Email:
New Preferred Customer Flyer: