A/B test subject lines, content, and send time the right way

Guessing what works wastes sends. Test one variable at a time on a big enough sample, run a 4-week subject-line series, and log every result so winners compound.

Opinions about subject lines are cheap; tests are truth. But a test only means something if you change one variable, have enough recipients per arm to be significant, and log the result. AI designs the 4-week test calendar and computes the detectable lift from your list size; you run it in your ESP and record the winners.