The Email Savant Series: How Much Email Is Too Much?

Mark Vogel

Written by Mark Vogel

July 10, 2018

What’s worse: over-mailing your list – which drives unsubscribes and disengagement – or under-mailing – which might mean lost opportunities to engage and convert?

Both can prevent you from meeting your goals. While most people will say “I receive too many emails!” I find that many brands might be under-mailing their audiences. Here are the issues with under- vs. over-mailing:

Issues with Over-Mailing

Issues with Under-Mailing

Industry Averages

How frequently do other brands send emails? Here are some average number of emails sent per month by industry, found in “The State of Email Marketing 2017” from GetResponse:

The average number of emails across all industries is about 5 emails each month. As you can see, there are wide ranges of frequency per month. How can you determine your best frequency?

Test, Test, Test!

In a recent installment of the Email Savant Series, I discussed A/B Split Testing – which included testing for frequency. Let’s investigate this further:

Every brand is unique. While the averages above can give you some general direction, it is important to truly understand what your particular recipients want. Start by setting some goals. Have you been concerned that your unsubscribe rate is too high? Then you’ll want to test a less-frequent series vs. your current schedule. Make a list of several measurables where you believe you might see improvement.

List Size

You’ll need to pull out a portion of your list to use as the sample group, and that group needs to be large enough to deliver reliable, statistically-accurate results. How large? Rather than diving into a dissertation on advanced statistics, let’s just say your test and control groups should each be at least 250 or more for each test. So, if your entire email marketing database is 1000 records or fewer, then A/B testing might not provide reliable results. Since you don’t want to engage your entire list in the test, because you want to save the positive results for the bulk of your list, then the A plus B totals should be less than half your master list.
Make sure your test group is a broad cross-section of your entire list. Don’t just pull out a batch from one state, or from all customers or all prospects.


There will be a variety of key performance indicators you’ll be watching in your frequency tests – open rate, click-through rate, click-to-open rate, and unsubscribe rate. Be aware of any other metrics that might demonstrate success. If a call-to-action in the message is to pick up a phone and call, then you should monitor any differences in incoming call volume between A and B.

Length of Test

Allow enough time to elapse to ensure accurate results. On average, how long after each send do you continue to receive opens and clicks? If you’re currently emailing only once a month, then you should wait at least another month before performing further testing.
If your list is large enough, keep repeating the tests until you see a decline in results. If you are mailing monthly, then test the monthly group against an every-other-week group. Then test against a once-a-week group. Then against a twice-a-week group.

Compare Apples to Apples

Make sure your two test groups are identical in every way other than frequency – same subject lines, same call-to-action, same message design, same time-of-day, and so on. This might be a challenge since the content in a once-a-month email won’t necessarily be repeated exactly each time for the tests. But find ways to ensure similarity between both groups and avoid adding any other variables that might affect results.
Most email marketing programs provide an automated A/B split testing mechanism. Monitor your key performance indicators carefully so you can act if you see any obvious changes in the metrics – either positive or negative.

Mark Vogel is president of Vogel Marketing Solutions LLC and serves as a lead email consultant for Nxtbook Media. He has more than 35 years of experience in the marketing world and has been actively engaged in email campaigns for more than 20 years. His email marketing clients include Fortune 500 companies, e-commerce retailers, non-profits, local businesses, and more. He can be reached at

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