customer mailing list

I have created a list under "accounts" of active customers from a field that identify who is a customer so that I can send email to that list. However I need to create a list of the customer *contacts* so that I can send mass mailing to this group. Under "contact" I don't have the field that allows me to select who are the active customers, it is only under "accounts". How do I then create the "contacts" list of active customers? Thank you much.