Mass email marketing works best when sending to people who already know you, your company, your products or services. Buying an email list of people who do not know you typically has a similar rate of response to paper mailings from a purchased postal list.
The rate of response is relative to the accurateness of the names and addresses on the list. Another tactic for doing email marketing to people who do not know you is to use a personalized approach. There are tools out there which do “drip” email marketing where one personalized email gets sent versus a common email to many.