Where Should You Focus Your Testing Efforts?

Between buggy support for HTML and CSS, spelling errors, bad links, missing images, and other potential blunders, it’s crucial to test your email campaigns before every single send. But, where should you focus your testing efforts? With so many email apps available (not to mention the different versions of each), it’s easy to feel overwhelmed trying to test every possible combination. Looking at open data for your audience is the key to narrowing down where you should be focusing your testing efforts.