Case Study: Boosting your Reach With an E-mail Series

In marketing, there’s a saying that people need to see your message three to five times before it sinks in. There are also some things you want to express that are somewhat complicated, so being able to feed the key benefits to readers in small bites helps with comprehension. In these instances and others, a series of e-mail messages can often be more effective than a single missive. Here’s an example of an e-mail series that increased unique metrics by 100 percent or more, broadening the reach of the message.

First, a word about terms. When I say “series,” I’m talking about developing a group of different but related e-mail messages sent over a span of time. In this case study, we developed six different e-mail messages that were sent in order, two weeks apart, to the same list.

Each message had unique information but built on the content of the prior message. Each of the six messages had the same links, in the same order and location (most in the left column of the creative) and the same calls to action. What differed in each was the body copy supporting the end goal.

The six e-mail messages had similar open and click-through rates; none stood out as exceptional. But the power of this approach becomes clear when an analysis to identify unique opens and clicks over the entire series is done.

First, let’s look at opens. Although the open rate was more or less consistent across all sends, the overall analysis shows that we were reaching new people with each e-mail message. After the second send, the cumulative number of unique opens (one open per subscriber) increased by 31 percent.

While the magnitude of the send-over-send lift in opens gradually decreased, we were still reaching new people even with the last e-mail message. If this client had stopped after the first send, the total open reach would have been roughly half of what it was thanks to the series (see the full results below).

E-mail 1 E-mail 2 E-mail 3 E-mail 4 E-mail 5 E-mail 6
Unique opens (cumulative) 6,541 8,547 9,944 11,199 12,068 12,772
Lift send over send (#) 2,006 1,397 1,255 869 704
Lift send over send (%) 31% 16% 13% 8% 6%
Average lift 10.6%

We saw similar results with click-throughs. The unique cumulative click-through reach actually grew by 63 percent after the second send; by the end of the series the client had received clicks from more than three times the unique subscribers than had clicked on the first e-mail message.

Once again, the lift gradually decreased but it still grew by over 10 percent on the last send. The lift in cumulative unique click-throughs was nearly double that of the lift in cumulative unique open rate for most sends, suggesting that there were people that had previously opened but not clicked who were motivated to do so thanks to the additional e-mail messages in the series (full results below).

E-mail 1 E-mail 2 E-mail 3 E-mail 4 E-mail 5 E-mail 6
Unique clicks (cumulative) 473 771 1,011 1,236 1,450 1,589
Lift send over send (#) 298 240 225 214 139
Lift send over send (%) 63% 31% 22% 17% 10%
Average lift 20.1%

The power of an e-mail series is even more evident when you look at individual link performance. The results, below, are for a single link that appeared in all e-mail messages in the series. After the second send, the number of unique subscribers that had clicked on it increased by over 100 percent; after the third e-mail, the lift increased by another 47 percent. By the end of the series, the number of unique people clicking on this link was nearly five times what would have been achieved with a single send.

One Link in the E-mail
E-mail 1 E-mail 2 E-mail 3 E-mail 4 E-mail 5 E-mail 6
Unique clicks (cumulative) 73 150 220 284 334 359
Lift send over send (#) 77 70 64 50 25
Lift send over send (%) 105% 47% 29% 18% 7%
Average lift 25.2%

E-mail series take a little more thought and a little more work to produce, but if you’re looking to effectively communicate a complex message and drive action, they are well worth the effort. The key is to make each e-mail stand on its own but also build on the messages in previous missives. Each reader has her own set of “hot buttons.” Sending a series give you the opportunity to build not just one case for the open, but many, in order to engage as many of the people on your list as possible.

The next time you’re thinking in terms of a single e-mail, give some thought to creating an e-mail series. It could boost your reach — and your bottom line — significantly.

Until next time,


Related reading

Vector illustration in simple linear flat style and bright yellow color - hand with mobile phone and finger touching screen - app with message.
Close-up of a person's hand on a laptop keyboard, with neon closed envelope email icons floating around their fingers.