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A.R.P.E.S.: The most important email marketing metric ever

When evaluating the success of an email marketing strategy, there is a lot to consider.


Opens, clicks, clicks thru, click to open rate, hard bounces, soft bounces… the list goes on.

Opens and clicks are great. They show us that we are succeeding at engaging our audiences (to some extent). Other stats can lead us to key conclusions about the quality of our mailing list, subject lines, calls to action and design. This is all great information to have.

But what are we, as email marketers, really hoping to achieve when we hit the “send” button? What is our true purpose? Why are we doing what we’re doing?

Such existential musings may seem more at home in a first year philosophy class than they do on an email marketing blog, but we believe they are worth asking ourselves from time to time. To step back and evaluate our goals and ask ourselves some tough questions about how our email marketing efforts are lining up with those goals on a day-to-day basis.

So, what is our goal?

To make money, right?


It should be.

We are either endeavouring to make money for ourselves, or to make money for someone else who then gives us some of it in the form of a paycheck.

In either case, the more money our marketing emails make, the better. It’s not rocket surgery.

Do something, make money, and reap the rewards. Do something better than everyone else is doing it, make more money, reap more rewards. Capitalism at its finest.


Image credit: Nickelodeon



The more efficiently we make money, the bigger the rewards are. In email marketing, the more efficiently our marketing emails generate revenue, the bigger the rewards are.

If only there was a way that we could measure that efficiency effectively…

There’s a stat for that.

A.R.P.E.S.: The most important email marketing metric ever

For our money (and we do have some) A.R.P.E.S., or average revenue per email sent, is the one stat which truly measures the overall efficiency and effectiveness of an email marketing campaign.

What it is

It is pretty simple to calculate. You take the total amount of email marketing revenue generated by a campaign and divide it by the total number of marketing emails sent in that campaign.

This will give you a number. That number is the average revenue per email sent (A.R.P.E.S.) of that particular campaign.

Image credit: Universal Pictures


What it tells us

A.R.P.E.S. can give us the clearest indication possible of how well our marketing emails function in terms of achieving our ultimate goal of generating revenue (making money). Campaigns with a higher average revenue per email sent can be said to be the most efficient use of our email marketing time.

There are voices out there in the email marketing world that simply call for emails and more emails. They tell us that the more emails we send, the more money we will make and that, ipso facto, sending massive amounts of emails is the best way forward, but this strategy ignores several key facts:

  1. Mailing lists are not infinite
  2. Oversaturating a mailing list will annoy people, damage your brand and cause your audience to either unsubscribe or ignore your emails
  3. No matter how many times you send a bad marketing email, it is still a bad marketing email

What A.R.P.E.S. does is give us some insight into what is working and what isn’t. A campaign with a gigantic mailing list will generate more revenue than one without a gigantic mailing list- that much is true. Unfortunately all we can glean from this information is that it would be nice to have a bigger mailing list, which, presumably, we already knew. A campaign with a low average revenue per email sent, on the other hand, indicates that there is a problem somewhere in our strategy in reaching the mailing list that we do have, and that we need to use some of email marketing’s lesser metrics to determine exactly what that problem is.

So how much A.R.P.E.S. is a good amount of A.R.P.E.S.?

It’s tough to say…

A.R.P.E.S. varies widely across industries in this field, and can be affected by any number of factors for a particular business. Better questions to ask are: Which of our company’s campaigns had a higher A.R.P.E.S. than the others, and which ones had a particularly low A.R.P.E.S. when measured against the others?

Answering these questions, and taking a good hard look at the results will enable us to identify trends within our audience and their habits when interacting with our emails. This opens the door to true optimisation in our future email marketing efforts.

And that is helpful information to have.

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Trevor Beers, Senior Language Technician, Phrasee

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