I read an interesting article on the strategy behind sending cold emails titled How To Write Cold Emails That Quickly Convert Sales in Entrepreneur magazine.  The author, John Rampton, identifies 9 key steps: 

1. Identification your target       

2. Identify their pain points

3. Get their address

4. Subject lines matter

5. Be brief

6. Be personal

7. Have a call to action

8. Follow Up

9. Test and Measure

What stood out to me the most was the concept of Test and Measure.  Similar to a Lean Startup Method for building a company, the whole goal behind this effort is to measure and adapt.  

 Find answers to these questions: (a) Which subjects worked the best, (b) what time of day worked the best, and (c) what content had the most responses. Small tweaks in the process can lead to big returns.