A/B test a subject line

A/B testing is on Growth and up.

On the Subject step, add a variant. Set the split percentage (the share of the list that gets the test) and the winner criterion (open rate or click rate). Mule Mail sends both variants to the test share, waits the window you set, then sends the winning subject to everyone else automatically.

Test one thing at a time. If you change the subject and the send time and the from name, you have learned nothing.