Great quote. 

Email is not an acquisition tool!  It is a relationship tool.  Something you use to develop a conversation with a prospect or customer. In fact, as Jim Nail, Former Senior Analyst with Forrester, said in a recent report:

“One of the real strengths of email is its ability to finish the customer acquisition job started by media advertising.  Once the customer has been attracted to the web site, email can move a prospect through the consideration and preference phases all the way to purchase.”

Source: AIMS Canada: From Acquisition to Developing Customer Relationships: Measure What Works