Engagement Metrics: Listen for the Sound of Customers Leaving

Some brands simply hang onto email subscribers better than others. They develop stronger relationships, more organic list growth, spend less on acquisition, and their customers’ lifetime values are higher — often dramatically so — than their competitors’. Among the differences between these leaders and the brands they outperform is systematic early intervention to anticipate and stem subscriber attrition. For many, engagement metrics are critical to detecting the first signs of flagging interest.

Virtually any marketer can expand the use of email metrics beyond opens and clicks into those used by mailbox providers to assess subscriber engagement. Here are three key engagement measures that winning email marketers monitor to get early indications of weakening customer relationships:

1. Deleted without reading: Your messages are being ignored. A significant uptick in this early warning metric is a clear indicator that subscribers are losing interest in your messages. If people who once valued your email aren’t taking the time to even open your messages, your relationship is in trouble. Now is the time, at the first sign of disinterest, to think about how to re-engage them. Tactics include retesting and possibly changing your subject lines, studying and adjusting sending frequency to audience segments that have begin ignoring more email, or re-evaluating timing to see if there’s a better day or time of day to engage key segments.

2. Complaints (AKA This is Spam, TIS): When subscribers flag your message as spam, your email relationship is over. Not only are they disconnecting from your brand, at least in this channel, but if enough of them start complaining, they're also harming your sender reputation. Spam complaints are the clearest signal to a mailbox provider that a sender’s email is unwelcome, and a spike in complaints can trigger corrective action as providers redirect mail to spam folders (or block it from reaching users at all) to keep it from bothering their members. Marketers can use complaint rates to their advantage, however, by correlating TIS patterns with program tests. Any changes, including reductions in complaints, provide clear, fast indications of how subscribers feel about new tactics.

3. Read rate: This is the easy one. No matter what else you want from your messages, people should read them. A decline in your read rate is the quickest, most obvious indication that subscriber engagement is falling off. It’s the first sign that something is wrong. Instead of letting these subscribers fade away or, worse, end your relationship with a complaint, target them with a reactivation campaign as though they’ve stopped engaging altogether. Then watch read rates to see what changes they respond to. Also, keep in mind that you’re not the only one watching read rates to gauge the health of this relationship. Mailbox providers are using exactly this metric to see how you engage with readers.

These metrics can help you identify and solve a real problem before it impacts the health of your customer relationships. While testing email optimization tactics can help you find the right approach to reactivating subscribers, there’s one more area to explore when you’re diagnosing flagging engagement: rendering. Declines in any of these metrics may be related to erosion in your user experience as messages fail to render properly in changing email clients and increasingly used mobile devices. Identifying (and fixing) a rendering problem could save you from tinkering with a program that’s otherwise not broken.

Tom Sather is the senior director of research at Return Path, an email marketing solution that helps to improve deliverability and ROI.