Subscriber retention rate = # subscribers – bounce backs – unsubscribes / # subscribers
How much do you stink? This is perhaps as strategic an analysis as you could do for your email campaigns. Here you are measuring both the technical effectiveness of your email campaigns over time (reducing bounce backs) and the relevance of your messages and the targeting of the same (reducing unsubscribes). Measure retention rate over time in aggregate – or for optimal health, segment retention rate – and measure it for the various objectives you have set for your email marketing program.