How Data Science Answers the Question, “When’s the Best Time to Send My Emails?”


Running your business can oftentimes feel like you’re flying a plane. Pilots manage a ton of different dials, knobs, and buttons that keep the plane safely in the air and headed in the right direction. For ecommerce marketers, those dials, knobs, and buttons are your open rates, campaign ideas, and marketing automation.

You try to pay attention to every metric and optimize every possible opportunity you have to grow your business. And on any given day, there are lots of choices you can make.

If you use Klaviyo, then it’s no secret how many dials, knobs, and buttons you can push to help improve your business. For example, you can create almost any customer experience you can imagine. Want to send a coupon to people who visited your site two hours ago, browsed socks, spent at least $50, and has never returned anything? You can easily do it! But should you? And is $50 the best threshold? How does that compare to other experiences you could create?

Growth-focused ecommerce marketers need the same thing those trusty pilots have when they’re flying a plane—automation. That’s why Klaviyo is developing new capabilities to automate your marketing experiments.

These new automations will continuously track your business, test results, and inform you when to make adjustments. We’ll release the first new automated feature—Smart Send Time—in the coming weeks.

What is Smart Send Time?

Smart Send Time helps you understand the best possible time to send your emails. We’re starting by solving send time optimization because it’s what customers told us they wanted. When we asked customers what new data science features they wanted to see, the most popular answer was, “Can you help me figure out the best time to send my emails?”

As a data science team, we set out to find the best way to answer that question. We worked with 35 different brands to test our send time optimization strategies. This extensive work led to the creation of our own Smart Send Time algorithm, which we developed after a year of research.

The new Smart Send Time algorithm leverages the “Explore and Exploit” philosophy for data science experimentation. It automatically sets up, executes, and analyzes a set of experiments—with no work needed on your part—and it then chooses the best send time from those tests.

Once the algorithm determines the optimal send time for your emails, it continues to run tests to ensure the send time remains optimal. Klaviyo’s new Smart Send Time feature handles all the experimental setup, math, and analysis behind the scenes. All you’ll have to do is click a button and your emails will be scheduled to send at the best possible time.

Smart Send Time has been in a private beta with 15 customers who saw a 10 percent average increase in email open rates. Additionally, the algorithm outperformed other send time optimization techniques by 4x. Here are the results from five of those beta customers (anonymized by their industry):

Anonymized Company's Industry Open Rate Before Smart Send Time Open Rate With Smart Send Time % Improvement
Home & Garden 19.3% 21.7% + 12.4%
Beauty & Cosmetics 14.2% 17.3% + 21.8%
Jewelry & Accessories 8.5% 9.1% + 7.1%
Fashion & Apparel 22.7% 25.5% + 12.3%
Health & Fitness 6.5% 6.7% + 3.1%

Smart Send Time will be available soon and we’ll share more information about how it works, why it works, and why it outperforms other standard send time optimization techniques. Stay tuned!

Wish you knew when your customers will make their next purchase? Learn how you can predict when your customers will reorder.

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