Email metrics show how a mailing performs, but their reliability has changed. Open rate is measured with an invisible image, and privacy-protection tools load it automatically, so the figures tend to be overstated and cannot be compared over time or between segments. Click-through rate, the number of completed actions, and revenue attributed to the campaign are more reliable, and these need to be measured with tagged links. It is also worth tracking the unsubscribe rate, complaint rate and bounce rate, because these threaten future deliverability. More useful than individual campaigns is comparing segments and the long-term trend. The goal is not the best figure, but finding out which topics and formats drive business, and repeating them. A useful addition is also tracking replies to the mailing, because a direct human response tends to be a stronger signal of interest than any automatically measured metric.
See also: Email Deliverability, Unsubscribe and complaint rate, Channel grouping.
