We’ve officially made it through to our last topic in our 12 Days of Holiday Sending series and no offense to the first three, but I think we saved the best for last–metrics! I mean how else are you supposed to prove the astonishing success of your email program if you have no stats to back up your claims? So today we’re opening our metrics section by talking about testing. I’m sure you’ve all heard how important testing is, but in the off-chance you haven’t, let me explain. Testing is what takes your email program to the next level. By sending out virtually the same email with one isolated variable changed, it allows you to directly attribute the greater success (or failure) of that email to that specific variable change. Constantly improving your email means happy recipients, happy recipients lead to happy customers, happy customers lead to great things for your business. What and How to Test Say you’re interested in increasing your open rate. You could test your from address, your subject line, or the pre-header, just to name a few. When you’re testing, it’s best to choose just one of these variables to test at a time. Otherwise, you won’t know which change you made had the most (or least) impact. Also remember that to reach a solid conclusion from your testing, you need a decent sample size of responses. And the more specific the element is that you’re testing, the bigger your sample size should be. The possibilities for testing are endless, so don’t get overwhelmed. And sometimes there won’t be a clear winner for every test, so don’t be discouraged! Remember that even though it will take you longer to test each variable one by one, it’s worth it in the long run. Knowing that your customer base responds better to subject lines with a little mystery over a direct “what’s inside” is priceless! Your subscribers matter, and learning what they respond to best is just one way to show them you care. For more testing advice check out our guide on A/B testing and for more holiday sending tips review our SlideShare with all of our holiday sending tips!