To be successful in email strategy doesn't start with a communication strategy.  It starts with a framework for how you'll make decisions.  

Here are some elements that should be included in this framework: 

1. What are your monetary goals and objectives for your program, and how do they change by segment and/or product mix? 
2. What are the consumer actions and motivators that drive a purchase decision? Not just, why do they buy? But, what motivates them to buy, what type of information do they need in what part of the lifecycle?  How does it evolve by segment?  What type of support does your site, call center, or sales force play in this?  What are the tasks your customer must take to complete a purchase -- and how does your operations support those?
3. What competitive considerations are important to your business -- and how do they impact the ways your customers make decisions? How will you gather this competitive insight, consumer response and make decisions on this information?. 
4. How you create customer segments is critical to effective strategy. It's critical that you create actionable segments that can be catered to in-program.  Just because you can create dynamically driven segments and event-driven communications doesn't mean you will have the time or resources to truly optimize all the segments. 
5. Lastly, your framework should include simple hypothesis-driven testing. Your strategic testing framework should include how often you'll test, what hypothesis you want to solve, and what are the actions you'll take once you've proven or disproven this thinking.

Continue reading this excellent article by David Baker here: MediaPost Publications Keys To Great Email Strategy 07/27/2009.