Case Study: How Six Flags’ Email Delivery Climbs To The Top

What if you could cut your delivery time by 80%?

Six Flags is the world’s largest regional theme park company, with 20 amazing parks across North America. And email is a big part of their business—they send over 250 million emails a year to guests, customers, and clients. From transactional sales notifications to marketing campaigns, Six Flags relies on email to communicate directly to their guests and get them excited about their next visit.

But in 2015, before they switched to GreenArrow, their email infrastructure was holding them back. Their previous list manager only allowed them to send 200K-300K emails per hour, which during peak sending times was not cutting it. And worse yet, it was no longer being actively developed, which meant they expect any new features or improvements.

Six Flags set about finding a replacement. They had six key criteria:

First, their management team was only interested in systems that it could self-host on one of its own servers. Second, it had to be capable of delivering at least a million messages per hour. These two criteria alone narrowed the options considerably. Third, the system needed to offer a robust API that allowed it to be closely integrated with the company’s various CRM platforms. Fourth, the system needed to offer tools and monitoring to help the company maximize deliverability. Fifth, Six Flags needed the company that offered the system to offer professional, around-the-clock emergency support. And finally, you guessed it — Six Flags wanted a system that was actively being developed and improved.

“We looked at a variety of different email products, and very few of them even came close to what GreenArrow was offering,” said Mark Kupferman, VP of Interactive Marketing for Six Flags. “GreenArrow not only did everything we needed to do, but it included a number of features that allowed us to take many of our programs to the next level. And all at a great price.”

In this post, we’ll show how GreenArrow has helped Six Flags succeed by delivering vastly superior performance, improving deliverability, offering robust and powerful APIs, and preventing headaches with game-changing features like Remote Lists and our Event Notification System.

Faster Than A Speeding Rollercoaster

The most quantifiable difference between GreenArrow and Six Flag’s old vendor is in the area of performance. Their old system maxed out at sending 200-300 thousand messages per hour, whereas GreenArrow enables Six Flags to send between 1.2 million and 2.4 million messages per hour.

“It used to take up to 18 hours to send out all of our emails even with staggered delivery schedules,” said Kupferman. “With GreenArrow, cut the email delivery time down to just 3-4 hours. This has strategically impacted how and when we send our emails and given us a lot more control of our delivery schedules.”

And as fast as that is, with a hardware upgrade, GreenArrow could send email even faster. That gives Six Flags room to grow their business without having to worry about whether their email infrastructure can keep pace.

Here are the six key areas that helped Six Flags:

  • The ram-queue reduces disk utilization by eliminating the need to write messages to disk unless they are deferred or throttled.
  • The DNS Cache eliminates duplicate DNS record looks ups, boosting performance and reducing network utilization.
  • Direct Injection allows GreenArrow Studio and SimpleMH to write messages straight to GreenArrow’s RAM queue without any intermediaries. This cuts out the middlemen which previously sat in front of the RAM queue and boosts performance.
  • Greenarrow-remote greatly reduces CPU overhead by using a single persistent process to perform the same SMTP delivery work that’s normally performed by multiple processes being launched on other MTAs.
  • The Studio Multiqueue feature allows for multiple messages to be written to the same RAM Queue file. Believe it or not, this provides a nice performance boost. RAM is fast, but there’s still overhead associated with creating files on it, and Multiqueue helps to reduce that overhead.
  • GreenArrow uses Redis to queue and process jobs, including bounce, click, and open processing. This allows for faster processing of requests since jobs don’t need to be processed immediately, and lower disk overhead since Redis operates primarily in RAM.

We’ve discussed performance in a few previous blog posts. If you haven’t read them, then Is Your Email Up To Speed? is a good primer.

Keeping Guests’ Attention With Deliverability

Of course, being able to send emails quickly doesn’t do you much good if your subscribers aren’t receiving them. That’s where both GreenArrow’s deliverability features and team come in for Six Flags. Here are some of the key features that Six Flags uses:

  • Some ISPs obviously accept email faster than others, so Throttling is used to ensure that GreenArrow delivers email at an appropriate rate to each ISP. GreenArrow’s Throttling settings provide a sensible set of defaults out of the box, which can be tuned for each customer’s environment.
  • Dynamic Delivery adjusts GreenArrow’s throttling rules on the fly, based on the acceptance, deferral, and bounce rates for each ISP from each of GreenArrow’s sending IP addresses.
  • GreenArrow’s bounce processor automatically classifies bounces and deactivates subscribers that it determines have bad addresses.
  • GreenArrow’s spam complaint processor automatically deactivates subscribers who generate spam complaints. We routed complaints from the feedback loops that Six Flag was already signed up for to GreenArrow’s spam complaint processor, and signed up for the feedback loops that Six Flags wasn’t already on.
  • GreenArrow’s unsubscribe link tracking system automatically deactivates subscribers who click on an unsubscribe link, or trigger a List-Unsubscribe header.

During the setup process, we recognized that Six Flags had already developed a positive reputation as a sender. Therefore, we encouraged them to hold onto that reputation by moving their old MTA’s sending IP addresses to GreenArrow, rather than starting from scratch.

Our systems administration team then coordinated the logistics of that move with Six Flags so that they could get back up to speed almost immediately. As a result, Six Flags told us that their deliverability had “significantly improved.” Always good to hear that!

Automating Tasks With Time-Saving APIs

GreenArrow has a number of APIs which allow Six Flags to automate tasks, including most of what can be done in GreenArrow’s web interfaces. Here are the top three ways that Six Flags uses our APIs:

1) Sending Transactional Emails

Six Flags uses GreenArrow Engine’s HTTP Submission API to send their transactional email. Each API call submits between 1 and 500 emails, which GreenArrow then delivers.

Six Flags could have used SMTP for this, and many of our customers do, but the HTTP Submission API offers performance advantages that Six Flags was able to take advantage of. These advantages include reduced latency (SMTP is a chatty protocol compared to HTTP), and reduced bandwidth utilization, thanks to gzip compression.

2) Managing Campaigns and Mailing Lists

Six Flags reduces administrative overhead by automating campaign, subscriber, and mailing list management. This includes programmatically sending campaigns and updating mailing lists.

3) Retrieving Stats

Using an API to send emails is great, but how do you know that they made it to their destination? That’s where GreenArrow Engine’s Stats API comes in. Six Flags uses that API to retrieve data on both campaigns and individual recipients. This includes data on what messages were successfully delivered, which ones bounced, and how many are still in the queue.

Preventing Headaches with Seamless Integration

Every organization has its own systems, and sometimes it’s necessary (for the sake of everyone’s sanity) to work directly with those systems rather than try to fight the machine.

Case in point: Six Flags already had a substantial amount of subscriber data hosted on a Microsoft SQL Server. “While we could have imported those subscribers into GreenArrow’s database, that would have required us to configure synchronization, which can be a fiddly mess at times. Rather, we configured Remote Lists, which allow GreenArrow to read subscriber data directly from Six Flags’ SQL Server. No synchronization issues to deal with,” said Kupferman. We say, win-win!

Six Flags also uses GreenArrow’s Event Notification System to have information pushed directly to their Microsoft SQL Server each time any of the following occur:

  • A subscriber opens an email or clicks link
  • A subscriber gets deactivated due to clicking an unsubscribe link, generating a spam complaint, or having a bad email address detected due to bounce(s)
  • An email sent to a subscriber bounces

This allows them to do things like analyze trends and deactivate subscribers without having to give up a crucial part of their infrastructure. Again, win-win!

What a thrilling joyride!

At GreenArrow, we’re proud to admit that we have some pretty cool customers. We usually do our software training remotely using GoToMeeting. Every once in a while we get the privilege of flying out to a customer’s location for some on-site training. So Six Flags, if you ever need some advanced training, we’ll meet you at Goliath! For anyone else, we’d love to support you on your own email delivery rollercoaster ride—anytime! How can we help?


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