The test results will show you which email helped you meet those marketing goals so that you can direct your efforts to the winning email.
In this case, you would set up each test email to go out to a portion of your mailing list—maybe you split it in half or send one version to a small sample. You should also set the metric or goal you’re trying to meet with this test. Are you looking to increase open rates? Decrease unsubscribes? The test results will show you which email helped you meet those marketing goals so that you can direct your efforts to the winning email.