Firstly collect a list of emails . The best way is to collect targeted mailing list from you own opt-in box.ie. your own customer/prospect or another way is you can easily copy from the Mass Add Page in Facebook. There are lots of ways to get free mailing list. millions of them available on the internet but you must know where to get them.
Copy your whole mailing list then login to your Facebook account and click the link below to invite friends:
http://www.facebook.com/invite.php
