Email adepts overwhelmingly agree that many marketers focus too much on how their audience reacts to individual campaigns and not enough on their audience's lifetime value – a problem usually caused by deluging them with too many emails. "The better approach is to consider the effect too many emails will have on an email subscriber's lifetime value," says Jordie van Rijn, email marketing consultant and founder of Email Monday and Emailvendorselection.com. "The threshold until you see a decline can be as high as four to six emails per week. Once you exceed that threshold, you're likely to see a spike in recipients ignoring or even blocking your electronic missives."

To calculate the lifetime value of subscribers (LVS), first divide the total of your email marketing goal (e.g., purchases, downloads, requests for information) by the average number of active subscribers in your database during the previous year. Next, take that number and multiply it by the average lifetime of an email address in your database (for example, two years). The sum you get is your subscribers' lifetime value. In other words, the longer you keep subscribers engaged with you and your content, the higher that multiplier – and therefore your LVS – will be.

Like milk and a vase of roses, your email marketing list decays quickly. According to Annette Palmieri, growth marketing specialist for BEE Content Design Inc., a provider of tools for designing digital content, most email lists expire at a rate of about 22 percent each year. And given the amount of turnover that occurred during the pandemic, it's more than probable that rate of expiration exponentially increased over the past three years. That means it's more vital than ever to pay close attention to the ever-changing flow in the number of subscribers.

"To do that, you need to monitor the rate at which your email list is growing and shrinking, and make sure it isn't decaying faster than it's growing," Palmieri says. If your list is suffering a net loss of subscribers, Palmieri recommends gating your most downloaded or most visited content to increase its perceived value, a tactic that can prove useful in maintaining or growing your list size.

Marketers never have enough of the one resource they cannot make more of: time. They're often expending worth-its-weight-in-platinum time for relatively little payoff. To cut down on this chronological expenditure, van Rijn recommends monitoring how much time you're spending on email marketing, then automating as much of it as possible. Just as your return on investment goes up if you decrease costs while maintaining your level of return, so too does your return on time invested if you're expending fewer hours executing your email-marketing campaigns.

Although there is no hard rule of thumb here, van Rijn suggests that marketers spend about 20 percent too much time on their email marketing. So aim for a 20-percent increase in efficiency, and you're likely on the right track. If automation simply isn't possible, he recommends creating and employing templates and similar time-saving tools to ensure you get more done in less time.

An often-overlooked metric is the spam complaint rate, which indicates how many subscribers are marking your email as detested spam. "Companies should keep their rates at which this occurs to one subscriber out of every 1,000," Palmieri says. Your email service provider should be able to share data regarding how many recipients are nuking your emails. If your spam rate rises above that 0.1-percent threshold, it's time to reevaluate your efforts. Some of the most common causes include outdated contact lists and sender names that aren't easily recognizable to recipients. So try scrubbing your database and sending your company missives from a well-known company representative (or recipients' regional sales reps) to ensure that they can easily identify the sender as a real individual versus a spambot.

Return to Sender
While some email metrics are undervalued, others are equally overvalued, possibly distorting how you view your email campaigns' effectiveness. Here are a trio of measurements experts say you should click "delete" on.
Out of all the metrics, the open rate may be the most erratic. "Open rates can easily be manipulated by intentionally using tactics such as clickbait subject lines," says Kath Pay, CEO of Holistic Email Marketing Ltd., "or even unintentionally using a misleading, generic subject line." Pay notes that many A/B split tests show that generic subject lines receive a higher open rate, but consequently a lower click-thru rate than specific subject lines. This means your recipients open the missives but take no further action, reducing the metric's usefulness. In fact, such tactics can sometimes backfire as recipients begin to lose trust that your emails will deliver on their subject-line promises or – even worse – feel duped by your misleading subject lines. The takeaway: While open rate is an enticing metric, it should be complemented by other measurements to judge engagement.

Click-thru metrics are commonly used to gauge the effectiveness of an email campaign. But according to Cynthia Price, senior vice president of marketing at Litmus Software Ltd., an email design and analytics firm, they have an inherent weakness. "Due to privacy restrictions, such as Apple Mail Privacy Protection, IP addresses can often be hidden from the senders, and recipients can privately download remote content in the background." This makes it difficult – if not downright impossible – to obtain an accurate metric and could skew any numbers you're gleaning from an email campaign and lead to misdirected actions based on incorrect data.

When marketers begin delivering increasingly relevant content to their core audience that is more and more targeted, the quantity of emails issued becomes less germane. "The number of emails sent for each successive campaign should come down," says Skip Fidura, digital marketer and fractional CMO for business-to-business tech companies. He argues the problem with the emails-sent metric is that it hides the subscribers who don't receive the communication for various reasons or simply ignore it. E