Email Testing Best Practice : Image Testing
The key to A/B test an email is to test one component at one time. Changing multiple component may lead to confusion and will be difficult to analyze its impact. Make sure that you're testing a pure A/B split of your list and don't make any other variable changes other than the change in the image. You're looking to see if making a change in how you display and choose images can improve your email performance. You can't do that if you change other factors at the same time.
Also, be sure to use similar alt and title text behind the images of your testing emails. For email clients that don't load images, the alt and title text can impact performance significantly. Don't allow changes in alt or title tags to make the data in your test unclear.
Finally, be sure to plan out your image tests so that you know what you're testing when. Consider starting with placement or density and then moving on to image type or color or any other attribute.
Also, be sure to use similar alt and title text behind the images of your testing emails. For email clients that don't load images, the alt and title text can impact performance significantly. Don't allow changes in alt or title tags to make the data in your test unclear.
Finally, be sure to plan out your image tests so that you know what you're testing when. Consider starting with placement or density and then moving on to image type or color or any other attribute.