MarketingExperiments Blog: Research-driven optimization, testing, and marketing ideas

Sending more than 1.2 billion emails per year is a significant marketing investment. And for one of our Research Partners, this effort raised several questions:

• When will their list get irritated?
• How many emails should be sent on a regular basis?
• At what point do emails start hurting sales?

To ensure they were getting the most value from their marketing spend, our Research Partner wanted definitive, data-driven answers. So we tested for the optimal frequency that will maximize total revenue. While our scientists now have the benefit of reams of information and know the answer to these questions, we thought it would be a fun challenge to your “marketer’s gut” to test your acumen and see if you could spot a winner based on sheer intuition (and yes, there is a prize).

Background: The Research Partner is a large ecommerce company that sells well-known, inexpensive, perishable products online (if we told you any more we’d have to kill you). They had a massive, yet varying email send rate and was emailing the house list anywhere from once a week to four times a week. Most of the Research Partner’s strategy was based on the offers available at the time. With such variance in frequency, we wondered if sending more email messages would have overly negative effects on unsubscribe rates. And likewise, we wondered how much impact sending fewer emails would have on revenue. Ultimately, we were looking for that optimal email-sending sweet spot.

Test Design: We took a small, highly-motivated segment of the Research Partner’s house list and used it as our testing sample. We then split that list into seven segments that would receive different send frequencies as represented below:

Segment 1: 1X PER MONTH

Segment 2: 2X PER MONTH

Segment 3: 3X PER MONTH

Segment 4: 4X PER MONTH

Segment 5: 6X PER MONTH

Segment 6: 10X PER MONTH

Segment 7: 15X PER MONTH

We monitored the effect of the send frequencies for 60 days. We tracked delivery, open rates, click-through, conversion, revenue, spam complaints, and unsubscribe rates throughout the duration test.

Results: Testing for optimal frequency assumes that revenue and unsubscribes will increase at a steady rate until the list gets irritated. At that point, revenue will experience diminishing returns and even decrease. Likewise, unsubscribe rates will increase at that point of irritation.

We wanted to test the validity of this assumption, as well as discover the optimal email frequency for this company’s email list that increased both total revenue and lifetime value of the customer.

But before we reveal the results from our scientists’ brains, we want to test your “marketing gut” with the following question (Oh, and just to spice things up a little, one person’s intuition will get them a free seat in one of our online certification courses – normally $595.):

1. What is the optimal monthly send frequency for this company?
   1. 1-2 per month
   2. 3-5 per month
   3. 6-9 per month
   4. 10-15 per month

Congratulations to Sharon Mostyn, winner of the Email Frequency Contest, and one of only a handful of correct responses. Sharon chose the Landing Page Optimization Course as her prize. Subscribe to the MarketingExperiments Journal to be notified when the web clinic replay and research brief are available so you can see the correct answer along with a full analysis of how this discovery can help you shape your email campaigns.

To enter the contest, leave your choice as a comment to this blog post along with your email address or Twitter handle (make sure you’re following @MktgExperiments so we can reach you). We will select a winner randomly from the correct responses (and yes there is a correct answer). The winner and results for this test will be announced live on Wednesday afternoon at 4 p.m. EST during our free web clinic – Optimize your Email in Three Steps: How one marketer tripled revenue from their house list.

Categories: Analytics & Testing, Clinic Notes, Email Marketing, General, Research Topics Tags: B2C, clinic, Ecommerce, Email Marketing, email optimization, marketing, optimization, retail, shopping, webinar