Side-by-side comparison of deliverability of popular email sending services

In Email Marketing by Xu CuiLeave a Comment

When we send out emails, we want our emails to land in our recipients’ inbox, not their spam folder. We understand many factors can affect deliverability, including the email content, the match between content and recipients, the timing of the email and the size of list etc. However, assume we tried our best on our side, which email sending service should we choose to maximize the deliverability?

To this end, we compared the deliverability of the 5 most popular email sending services among biotech companies as well as 2 email service providers used by BizGenius. We randomly divided the subscribers into 7 groups, each with ~2000 recipients. Each group was assigned to an email service mentioned above. The content of the email is about a product which can be used in many research labs in the filed of biology and medicine. The emails were sent out at the same time (except for email service #3 and #4 due to technical issues). The data were collected a week after sending and all the metrics stabilized. We calculate the metrics (open rate and click rate) using the same method across different email sending services.

We want to emphasize that this study is within the field of biotech.

What is the result? As shown in the figure below, choice of email sending services makes a difference. The best email service can give us 3x more clicks than the worst one. The two email sending services BizGenius used are 50%-100% better than other services on average.

Comparison of click rate

Comparison of click rate

On the other hand, the open rate is roughly the same across all email services.

Comparison of open rate

Comparison of open rate

Independent study

The above result is verified by an independent study conducted by a company based in the state of Wisconsin, United States who targets researchers using mouse. They did side-by-side comparison between 2 email services and provider “A” used by BizGenius. Again, the email content and the sending time was identical. Using “A” almost doubled the click rate.

Comparison of click rate (independent study)

Comparison of click rate (independent study)

What might be the reason behind the difference between email services? All of the email sending service providers use reputable email servers, but it is possible that some institutes (e.g. Stanford University) may block emails from some providers. We have seen cases where emails to a certain institute are all blocked. To overcome this issue, we can use multiple providers to deliver our emails. For example, we can use provider A to deliver emails to Stanford University, and provider B to all other institutes.

Lesson Learned:

  1. Choice of an email sending service makes an difference in deliverability.
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