KPI in email marketing (and any other marketing strategy) stands for “key performance indicator.” These are the metrics you use to measure the effectiveness of your email campaign and whether it was a success. KPIs are always represented in a numerical format and are defined at the start of the campaign, and they should always be aligned with your campaign’s overall goal.
For instance, if your campaign goal is to increase engagement, a possible KPI is to increase your click-through rate by 20%. Other examples of email marketing KPIs are increases in conversion rates (CTR) and return on investment (ROI), or reducing cost per email.