How often should you split test an email?

by | Fri 16 Apr, 21

The top tools used for email campaign planning, from the top email marketing experts.

How often should you split test your email campaigns? Always, sometimes, rarely? This post looks at the best practices for split testing from some of the leading email marketing experts.

Test small, test often. Focus on small simple tests, like a word change or using an emoji, if you do broad-stroke tests you won’t know what the winning formula is. Test subject lines to improve your open rates.
Doug Dennison, CEO at MailNinja and owner of Chimp Essentials

If you work with large audiences, it’s always worth experimenting with different versions and send the one that performs best. Testing should be a habit, although I know that when you’re short of time you want to deliver as fast as possible, and experimenting looks like a luxury!
Alessandra Farabegoli, Digital Strategist, Co-Founder at Digital Update and Freelancecamp Italia

Every. Time. At Spike, AB Testing stands Always Be Testing. Once you have a consistent frequency you can then test and run experiments constantly either using part or all of your customer database. That way you’re always improving your response and getting as close as you can to be sending the right stuff to the right people at the right time.

Glenn Edley, Director & Email Strategist at Spike

As your list size allows, you should split test every campaign. Larger lists can test a variety of components more easily, as the reduction in subscriber count can make the information unreliable with smaller lists. But even a smaller list can still test subject lines or one area that can feed the data and knowledge for subsequent campaigns.

MaryAnn Pfeiffer, Digital Marketing Strategist at 108 Degrees Digital Marketing

Every campaign, test your subject line. What you think is interesting and would make you open an email may not be the same for your audience.

Frequently test your send day and time. I like to use Mailchimp’s time optimizer to get the hour correct, but I try different days. I find that weekend sends are frequently opened more no matter what industry you’re in.

Amy Hall, Email Marketing Strategist and Certified Mailchimp Partner at

Here’s the thing. This is a tool that has no downside in using. Why not test these important variables as much as possible? It takes a lot of testing to really gather a conclusion about the best send time for your Audience. Every campaign should be setup as an AB test.
Emily Ryan, Co-Founder and Email Strategist at Westfield Creative

You should run A/B testing as often as possible, as long as you have enough data to make results statistically significant. If not, run multiple tests until a clear winner emerges.
Adam Q. Holden-Bache, Director of Email Marketing at Enventys Partners

Every day is a school day…. and considering Mailchimp makes it soo easy to test, it makes sense not to take advantage of it.

However, if you’ve got a very small list, please avoid jumping to conclusions… look for indications over time… so test a series of emails, one with Emojii’s in the subject line, one without, and see over time if one works better… it’s easy to say “that one worked… I’ll use that all the time”, without getting ‘statistical validity’ (a posh way of saying it’s certain).

Robin Adams, Founder at Chimp Answers

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