Prior to SparkPost and AWS, we didn’t have the confidence that a new listing email would reach a user quickly. Now it’s right there, instantly.
Justin Farris Senior Group Manager for Growth, Zillow

Zillow revolutionized the residential real estate industry with a powerful online platform serving the entire lifecycle of buying, owning, and living in a home: buying, selling, renting, financing, remodeling, and more. It starts with the company’s living database of more than 110 million U.S. homes—including homes for sale, homes for rent, and homes not currently on the market. It also provides Zestimate home values, Rent Zestimates, and other home-related information. To power these services, Zillow migrated from its original colocated data center to Amazon Web Services (AWS).

One of the main ways Zillow communicates to customers is through email—up to hundreds of millions of messages each month. Because many real estate markets move from listing to offer in a matter of days, speed and deliverability are essential to meeting the needs of sellers and buyers. Additionally, email performance is critical to keeping Zillow users engaged with the platform.

As the company grew, it began experiencing performance problems with its email delivery provider. “They simply couldn’t handle our volume needs, especially during periods of high activity,” says Justin Farris, senior group manager for growth at Zillow. “For example, agents typically list open houses first thing Friday morning, which can increase email volume by a factor of 10 for several hours. The emails wouldn’t just be slow—they would get dropped completely, and we can’t have that.”

Zillow began discussions with SparkPost, an Advanced Technology Partner in the AWS Partner Network (APN) to assist in addressing these challenges. SparkPost delivers more than 25 percent of the world’s non-spam email and was able to demonstrate deliverability levels averaging 96 percent. Beyond technical capabilities, Zillow also felt SparkPost was a good choice from a strategic point of view. “SparkPost was interested in the unique challenges of our business and building smart, elegant solutions,” says Tara Clark, director of email for Zillow.

Since adopting the AWS-hosted SparkPost offering, Zillow has grown its email communications without scalability challenges. “We’ve greatly reduced the time it takes from content generation to email delivery,” Farris says. However, the benefits go far beyond better SLAs. “I manage the engineering teams, and with our email infrastructure on AWS, it’s so much easier and faster to build new emails, run tests, change features, and fix problems.”

Zillow has adopted a wide range of AWS technologies to maximize the power of its email infrastructure. The core components of its email-rendering system run on Amazon Elastic Compute Cloud (Amazon EC2) using a microservices architecture coordinated by Amazon Simple Queue Service (Amazon SQS) and Amazon Simple Notification Service (Amazon SNS). The company uses Auto Scaling to manage scalability of its email-rendering systems; Amazon Virtual Private Cloud (Amazon VPC) to manage internal access across many AWS accounts; and Amazon Simple Storage Service (Amazon S3) to host static assets. Amazon Kinesis is used to ingest and process data.

Building on the AWS platform greatly simplifies the set of technologies Zillow must manage. “We used to use a SQL database as a messaging queue, which was a separate piece of technology we had to manage and maintain,” Farris recalls. “Now, we just use Amazon SQS for our email-rendering queue, and it gets passed directly to SparkPost. It’s so much easier.”

Developers are happier because cloud-based systems empower them to fix problems faster. “Before, if an email job didn’t run, we had to get technical specialists to dig into the problem and find out what went wrong,” Farris recalls. “With everything on AWS, it’s simple for any developer to fix problems. The morale of the team has increased tenfold. Our developers are motivated to work on innovating how we do email because they don’t have to spend all their time managing low-level issues.”

Zillow has also adopted advanced AWS services to take better advantage of its partnership with SparkPost. “They provide a near-real-time stream of user-event data, such as sends, deliveries, opens, and clicks,” Farris says. “In the past, our analytics package was slow and latent, but with AWS, we are using Amazon Kinesis to consume the data stream and process it into better home recommendations. We couldn’t even have considered doing something like that five years ago. Now, we can easily build interesting technologies and features to make better use of SparkPost capabilities.”

Perhaps the greatest benefit of partnering with SparkPost is that Zillow no longer has to worry about whether its emails will get through. “As a result of adopting SparkPost and investing in our AWS capabilities, we can focus on whether we’re sending the right emails, getting them built more quickly, and providing insights to decision makers that help them maximize the value of the channel,” Clark says. “SparkPost gives us visibility into the entire content life cycle at all levels of detail. I feel that SparkPost and AWS are a safe bet as a long-term investment for our company, one that sets us up for future success.”

According to Farris, the most important result is improved performance for Zillow customers. “Prior to SparkPost and AWS, we didn’t have the confidence that a new listing email would reach a user quickly. Now it’s right there, instantly. In hot real estate markets, that could make all the difference in getting the right home.”


SparkPost’s email API delivers fast, flexible email and analytics integration for any application or website, enabling development and product teams to focus on building applications rather than managing email servers. Its customers send over 3 trillion messages a year—more than 25 percent of the world’s non-spam email. SparkPost is an AWS Partner Network (APN) Advanced Technology Partner and a member of the AWS Marketing and Commerce Competency Program.

For more information, contact SparkPost through its listing on the APN Partner Solution Finder or on their website.