There are various types of test data you should focus on:
Subject Lines: Test different subject lines to see which one generates the highest open rate. Email Content: Experiment with different types of content, such as text versus images or short versus long copy. Design Elements: Test different design elements like layouts, fonts, and color schemes. Call-to-Actions (CTAs): Compare different CTAs to see which one results in the most clicks. Send Times: Test different days and times to determine when your audience is most likely to engage.