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Predicting Email Deliverability: The 9th Party Theory

As Internet Service Providers (ISPs) have continued to tighten filtering to eliminate spam through filters based on engagement levels, success in deliverability has become highly based on engagement. Many studies have been released on engagement rates across industries and industry average engagement rates are often used as an indicator or benchmark for sending.

However, these studies have left out an important element: each company has a truly unique business model that affects the overall engagement. I propose this model be looked at more closely as a consistent indicator of engagement and therefore, a better indicator of deliverability.

Allow me to introduce the 9th party theory to the email delivery lexicon.

Here’s the terminology we’ll work with:

Product / Service

Dyn Email Sending Graphic

The company is offering a 1st party product or service, meaning that they directly fulfill that product or service. This is different than a 3rd party product or service where an agent facilitates that fulfillment.

  • 1st party example: Best Buy sends you a coupon with their weekly specials.
  • 3rd party example: Groupon sends you an offer for a special at a local spa.


1st party recipients are those which have signed up directly with you, whereas a 3rd party might be part of a 3rd party offer opt-in, “forward to a friend”, or sites that allow management of groups like churches, employers or sports leagues.

  • 1st party example: sends you a notification that you’ve received a message from another member.
  • 3rd party example: A site you signed up with and selected to receive 3rd party offers has provided you a commercial offering.


I lead our email delivery team, providing enterprise email delivery for a multitude of clients on our DynECT Email Delivery platform. I compiled the above research through looking at averages across our platform from various senders. These senders were categorized by their business models and data was aggregated for the past 30 days for percent opened, clicked and the percentage of complaints per open.

The coloring in the image shows the predicted deliverability based on business model. Assuming you’re following best practices, you’ll naturally have better deliverability in the green areas than those in the red.

Here are the main points I’d like to point out from the chart:

  • 9th Party Sending: The combination of the 3rd product / service with the 3rd party recipients is a red flag for those looking for great deliverability. I’d like to refer to this as 9th party sending (3rd x 3rd). Even assuming CAN-SPAM compliance and best sending practices, the low engagement and high complaints per open combine for a deliverability nightmare.
  • 1st/3rd Party (High Engagement): The highest engagement rates can be found in the 1st and 3rd combinations. This makes sense as these are often daily deal sites or messages “on behalf of” a friend. Naturally, you will see a higher engagement through open and click rates on this mail and the complaints per open ratio is also low.
  • 1st Party Sending: The engagement rates are moderate which are mostly explained by newsletters and transactional mail that is often desired but not as engaging as special offers or coupons from the 1st / 3rd combinations. The reason this mail has high deliverability as compared to the 9th party sending is mainly due to its low complaints per open ratio.

The main takeaway is that engagement and the ratio of complaints per engaged user will mainly drive your deliverability, not the industry in which you are a part of.

9th party sending will likely cause issues in these areas and I question whether it’s really within the spirit of the CAN-SPAM Act. Some states have even passed additional laws to better detail out the intention of CAN SPAM like California has in Balsam v. Trancos.

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Whois: Mike Veilleux

Mike Veilleux is a Director of Product Management at Oracle Dyn Global Business Unit, a pioneer in managed DNS and a leader in cloud-based infrastructure that connects users with digital content and experiences across a global internet.

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