A marketer conducted an A/B test and expected the new version to perform better than...

The conclusion that the marketer can make about these A/B test results is that their test hypothesis was invalidated and they should test again. This means that their assumption about what would improve their email performance was not supported by the data and they should try a different variation or element to test. The test was not erroneous or too short, as long as it was set up correctly and ran for a sufficient time period to reach statistical significance