Before hitting the 'send' button, you see a confirmation page that provides a summary of the mailing. On this page there is a section named "About the Contact Source" and it give you a count of contacts to be targeted; it also gives you the ability to hit a "refresh" icon to get the most recent count; however, it down not allow you to preview the list. It would be most beneficial to be able to get a preview of the email addresses within the contact source that you chose in an earlier screen, so that you can double check your mailing targeted email addresses before hitting the send key.