E-Mail Applied: Beware the Danger of High Frequency E-Mail

I had breakfast a little more than a year ago with the vice president of marketing for a major online retailer and cataloger. She told me she was worried she'd fallen into the trap of e-mailing too frequently. Her company was sending three or four e-mails per week. She noted that every e-mail generated sales — and that obviously pleased senior management.

But she was concerned that the quantity she was sending was hurting her list. Today, after careful analysis, the company usually sends one e-mail a week.

Every e-mail you send will generate sales, but how do you find the right cadence for your list?

Frequency Pros and Cons
No doubt, it's categorically true that a strong e-mail contact strategy with compelling offers will generate sales. At the same time, industry consumer surveys have shown that one major reason for opt-outs is frequency of contact.

There's a way to measure the impact on your business. If you step up frequency of mailing during the holiday gift-giving season, for example, you can compare those results with the times you send fewer e-mails. Or, you could create a holdout group that receives fewer e-mails and track both groups over several months. Or, even if you don't create separate groups, you can monitor activity to help determine whether your current frequency schedule is working.

Below are some metrics you should be watching. Aggregate this activity on a monthly basis, do simple trend analysis and project what this might mean to your company over a full year based on your current list size. Keep in mind that new additions to your list can mask performance issues and list fatigue.

• Revenue increase. This likely will be stronger with a stepped-up mailing schedule. Are you trading short-term revenue gains for long-term losses?
• Revenue per delivered e-mail. This is the statistic that tells all.
• Opt-outs. Does frequency have a direct impact on your list size?
• Spam complaints. High complaint rates put your e-mails in danger of being blocked by ISPs or sent to bulk folders.
• Bounces. If you're sending more e-mails, naturally you'll have more bounces. As a result, more of your list will be moved to a do-not-e-mail status over time.
• Open and clickthrough behavior. If you don't get opens, you're not engaging your list. Mailing to a list that's increasingly inactive can be a problem. Plus, low open rates impact your reputation with some ISPs.

This analysis takes time and discipline, but yields an assessment of your e-mail program's health. I've seen examples of 40 percent revenue increases with more frequent e-mails. But the revenue per delivered e-mail is about half, and opt-outs are more than double.