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Q3'05 eROI Email Statistics by List Size

eROI did an interesting study on the effect list size had on read and click statistics in Q3. They found that the middle of the week is the low point and Sunday and Friday are noticeabe high points in the week for both stats. Sending volume is thus inversely related to how reads and clicks are going to react, with the exception of Saturday.

This quarter eROI decided to take a different look at day of the week stats, namely by adding list size to the equasion. They broke down lists into:

  • <500
  • 500-999
  • 1,000-4,999
  • 5,000-9,999
  • 10,000-24,999
  • 25,000-49,999
  • 50,000-99,999
  • 100,000-199,999
  • 200,000 and higher

They found many expected themes that reads and clicks decline and bounce rate increases. The reasons for this are simply that of list management, larger lists require more maintenance and make individual accuracy more difficult. Smaller lists are easily managed by marketing managers.

eROI therefore recommends to look at creating smaller segments of customers to treat differently or, even better, utilize dynamic data to address your customers. Consider removing individuals that are not reading your emails or separate them out into a different segment and mail to them less frequently and see how that affects your overall successfulness of your campaigns.

I agree with these recommendations, the more relevant the message is to the recipient, the higher your reads and clicks will be. I wouldn't necessarily mail the individuals that are not reading your emails less frequently but I would certainly try to find out what makes them tick so that I can provide them with more relevant content.

Download the complete .pdf

This data used for this study is global, so it's not US centric. Find past eROI studies for comparisons here: and subscribe to their Email Strategies Newsletter at

Source: A special thanks to Dylan T. Boyd, VP of Sales & Strategy at eROI for bringing this interesting study to my attention!

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