In the winter of 1860, a Vermont-native by the name of William Hepburn Russell teamed with two business partners to create the Pony Express—a fast mail service that proposed to significantly cut down the amount of time it took to get a letter from St. Joseph, Missouri, to Sacramento, California, by using a number of mounted riders instead of a stagecoach.

10 days, Russell and his partners promised. That’s all it would take.

It was a radical idea, and was a success in that it met its promise, but a failure in that it shuttered after 18 months, just two days after the completion of the first transcontinental telegraph, a technology that allowed for near-instantaneous communication.

“Interesting story, Dave,” you’re probably thinking, “but what’s this got to do with email?”

Glad you asked. If you’re an email marketer, this as good a place as any to stop and reflect on the undoing of Russell and his business venture. Because, in a lot of ways, your email marketing program is remarkably similar to the Pony Express: it’s too slow.

Think about it: by the time you hit “send,” by the time your email hits your customers’ inboxes, by the time they actually get around to opening it, something has changed. It could be something in a specific customer’s context or it could be something about the message you sent.

Whatever it is, though, it’s hurting email.

Consider:

The median unsubscribe rate for a retail brand is .084%, and roughly 50% of most brands’ email databases are inactive, or people who never engage with your email. If your list size is 1 million customers, you send two emails per week and are spending $3 to acquire every name in your database, that means, over the course of a year, you’re wasting $1.2 million of your email acquisition spend every year.

Add that to lost opportunity cost, and you can begin to see the need for change.

Continuing with our hypothetical, yet conservative, math game… if your average conversion event brings in $50, just getting 1% of those lost customers to buy a product, sign up for your service or invest in your business, means an extra $2.1 million in revenue. Wow.

The cause of that effect is the same thing that spelled the end of the Pony Express. If your email can’t keep up with your customers’ changing contexts, or keep your message up to date, how can you be relevant—and build a meaningful relationship— with your customer?

You can’t.

Many email marketers have realized this. In what’s a real and normal response, they’re sending more emails, more frequently, under the pressure of hitting key metric goals and trying to meet their customers “in the moment.”

Though they’ve recognized the problem, they’re taking the wrong approach to finding a solution.

To drive engagement, and business success, email needs to be a relevant means of communication, not the modern-day equivalent of some outdated letter carried across the country by a rotating series of horses and riders.

The solution to getting there, though, starts with rethinking how that message actually gets delivered.

While traditional email content is served at the time a marketer hits send, new tech let you serve content when a customer actually opens an email. At Monetate, we’re calling this open-time personalization technology. Others are calling it dynamic email or agile email, but, in the end, it’s the same idea.

It’s a new way of thinking about email optimization and digital personalization, letting you reach your customers with messages that are truly relevant to their context at that very moment, not just past behaviors.

Here’s a real-world example.

Last week, I got this email from Urban Outfitters:

On my iPhone.

Think about that for a minute: an email, promoting a new Android App, hit my iPhone. What good is that to me? If you can’t offer me a relevant email experience, why am I going to continue opening your emails?

Open-time personalization solves this problem.

Instead of sending me this email, Urban Outfitters could have simply excluded iPhone users from receiving the email. Within the Monetate UI, it’s as easy as targeting Android phones from a dropdown menu, adding the snippet of code to your ESP, and hitting send.

It’s tactics like these that are having a significant impact on email effectiveness.

Marketers using open-time personalization are seeing lifts of 300% and higher when it comes to click-throughs and, according to a recent Econsultancy report, are 57% more likely to report conversion rates higher than industry average. Shoppers, too, support the tactics. According to a recent Harris Interactive survey, 82% of shoppers have said they would buy more from a brand if the email they received was personalized.

What’s all this mean?

It’s really quite simple: you need to be focused on getting your email program up to speed. Otherwise, you’re likely to join Russell and company in the list of those who were caught from behind.