What to test? When to test? How to test? Questions for the ages! It's a little hard for me to tell you without knowing what your mail quantity is, but I'm going to suggest something that may take away the sting of an A/B split test. First, do a control test vs. an A vs. B test. That's right, a true test will take equal-sized blocks of your housefile and devote each one to a control (i.e., no offer) vs. an A and a B.