How additional space in an email template affects unsubscribe rate Experiment ID: #11343


Experiment Summary

Timeframe: 12/31/2018 - 1/14/2019

EWTN was running their year-end campaign while building an email preferences center in their new email platform. A discussion about unsubscribes led to their team noticing that the email footer, which contained the unsubscribe link, was really close to the bottom of the message—possibly too close. They were curious to see if simply adding in more whitespace led to a reduced unsubscribe rate. They created a treatment that simply introduced 10 lines of whitespace to push the footer down, and split the file to see how it affected unsubscribes.

Research Question

How will lowering the footer in the email template through increased white space affect unsubscribe rate?


C: Version A
T1: Version B


Treatment Name Click Rate Relative Difference Confidence
C: Version A 0.44%
T1: Version B 0.35% -20.5% 99.6%

This experiment has a required sample size of 37,444 in order to be valid. Since the experiment had a total sample size of 163,132, and the level of confidence is above 95% the experiment results are valid.

Flux Metrics Affected

The Flux Metrics analyze the three primary metrics that affect revenue (traffic, conversion rate, and average gift). This experiment produced the following results:

    20.5% decrease in traffic
× 0% increase in conversion rate
× 0% increase in average gift

Key Learnings

The new template led to a 20.5% reduction in unsubscribes—which meant more people stayed on file. This included “native” unsubscribes from Gmail and other platforms. Though this approach might eventually have long-term consequences for deliverability if email clients view these spaces unfavorably, they can be a tactical introduction to reduce unsubscribes during high-frequency email campaigns.

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Experiment Documented by...

Jeff Giddens

Jeff is the President at NextAfter. If you have any questions about this experiment or would like additional details not discussed above, please feel free to contact them directly.