How Netflix Sends Emails To Millions Of Users With Amazon SES
How does Netflix deliver hundreds of millions of emails per day?
Ifyou are a Netflix member, chances are you receive their promotional emails every time they suggest new, personalized content to watch.
Have you ever wondered how they do this and what powers this immense system that can send out over 260 million emails in a day or two?
Like most of Netflix’s infrastructure, AWS (Amazon Web Services) is behind this powerful email system.
Amazon Simple Email Service or SES, allows you to send out emails programmatically and pay very low prices per email sent.
Netflix has achieved very high inbox placement rates while delivering hundreds of millions of emails every day. [1]
The Story
Before using Amazon SES, Netflix was using an in-house solution to send out mass emails to its customer base.
This setup brought with it a lot of complexity as it required Netflix to provision and run servers to send out the emails.
They also had to provision these servers across multiple regions in the world and scale these out as well to handle sending high-volume emails.
Netflix doesn’t only send out promotional emails, they send:
Emails with personal account details, sensitive information like password resets
Emails with transactional information
Personalized recommendations of content
Marketing emails for old, new and future customers
Handling these different categories of email, all having different priorities, and scaling them out, posed a real challenge to Netflix.
Amazon SES To The Rescue
Netflix needed an email solution that could scale, be flexible, globally available, affordable, and delivery high-quality performance.
SES provides all of these benefits and more.
It was the perfect match.
Netflix released a statement saying:
We believed Amazon SES could help us be elastic, that we could pay as we went along, and that we could stop worrying about optimizing settings for each ISP. [1]
Let’s dissect this statement to demonstrate the true power of the cloud.
SES helped Netflix’s email-sending activities become elastic.
This is because, with the serverless nature of SES, the computing capacity of servers provisioned behind the scenes automatically scales up or down based on Netflix’s email-sending needs.
With more emails sent, SES provides higher scalability by provisioning more servers to send out emails.
However when sending fewer or no emails, the extra servers do not stick around idling for work, they automatically shut down. That is the definition of being elastic — and one of the greatest benefits of the cloud.
This leads to another benefit of SES, which is cost efficiency.
By being elastic and serverless, SES provides users with the most cost-efficient service by constantly and dynamically provisioning servers based on their usage.
In their own data centers, Netflix would have to purchase hundreds of server machines, a large upfront cost, and still pay for them even when the servers are idle and not sending any emails.
Finally, the fully managed aspect of SES, made it even more attractive for Netflix to benefit from.
With SES, they wouldn’t have to manage, patch, and maintain servers, optimize, or scale them up and down — a costly and time-consuming process.
How Netflix Uses SES Today
Netflix started by creating different pools of dedicated IP addresses, with each IP address pool responsible for sending out a particular email type.
For example, all marketing emails would be sent in one dedicated IP address pool.
With this setup, when Netflix wants to perform data analysis and track metrics such as open rate, engagement rate, and other similar user behaviors, they can isolate analytics by email type.
The purpose of this infrastructure, aside for data analytics is to be able to measure their metrics, like placement and bounce rate, and sender reputation.
Transactional emails that are sent to existing customers carry low risk since they are much less likely to be reported as spam or unsolicited emails.
While marketing emails sent to non-members carry a much higher risk of being reported.
Once Netflix was able to evaluate the impact of bounce rates, complaint rates, and its general reputation of sending out emails, they were confident enough to move all of its email infrastructure to SES.
The Results
To evaluate the effectiveness of SES, Netflix used a third-party tool to assess its inbox placement (emails that land in the customer’s inbox) and sender reputation scores.
The results showed that the inbox placement score had exceeded 99%, and the sender reputation stood at 97/100.
From these results, Netflix was able to shut down their on-premise email solution for good and migrate 100% of its email-sending activities to SES.
Another benefit Netflix found was the ability for SES to seamlessly integrate with other AWS services.
With SES, they were able to get feedback from Amazon SNS (a pub/sub notifications service) about deliveries, bounces, and complaints.
Conclusion
Netflix’s transition to Amazon SES has significantly optimized their email operations, providing elasticity, cost-efficiency, and high delivery performance.
By leveraging SES, Netflix has been able to achieve over near 100% inbox placement rates and a very high sender reputation score, allowing them to retire their complex and limited in-house solution.
The integration with other AWS services further enhances Netflix’s email infrastructure, ensuring reliable and efficient communication with their vast customer base.
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References
Netflix and Amazon SES Case Study. 2021. https://aws.amazon.com/solutions/case-studies/netflix-ses-case-study/