The Regular Newsletter can be tracked as you must have a User Record/Login to be able to sign up for one, and it will be tracked in the constituents record.

The Anonymous Newsletter cannot be tracked by it's nature, in accordance with the CAN-SPAM Legislation according to the Federal Trade Commission:
http://www.business.ftc.gov/documents/bus61-can-spam-act-compliance-guide-business

Newsletter recipients can be viewed after the newsletter is sent. The recipients tab of a newsletter can be compared to previous issues to see new recipients.