The 250ok Guide to Responsibly Migrating Email Service Providers (ESPs)

In 2017, we published the Email Service Provider (ESP) buyer’s journey. It’s one of our most popular blogs to this day. But in 2019, we find it’s not only about picking the right ESP to work with, but instead, understanding why you might need a new ESP in the first place.

Surely many brands split their traffic across multiple ESPs simply to build in protections, such as avoiding a full meltdown if one ESP experiences challenges or another ESP is more suited to a specific mail stream than another. But some brands just want something new and will abandon their current ESP to try different.

Marketers should better understand why they should (or should not) switch ESPs before embarking on the buyer’s journey. Do you simply misunderstand your current ESP’s data? Are deliverability issues a symptom of a larger problem than the “wrong” ESP? We’ll help you understand how to identify the right time to make the move, and how to do it the proper way to improve marketing success for your business.

We work with a lot of partner ESPs (SparkPost, Twilio SendGrid, and Adobe/Marketo, to name very few), and we work with all manner of marketers in various industries, so we’ve heard it all. Some reasons organizations switch ESPs are entirely valid and well-advised, yet sometimes, they’ve got it wrong. Here are a number of issues not worth jumping your ESP over.

Another ESP says our deliverability metrics are better than reported by our current ESP.
This is relative. First, deliverability is a many-headed beast not easily explained by simple reasoning. ESPs provide senders with the proper infrastructure, authentication, and tools to deploy mail; senders own their reputation and deliverability. Poor practices lead to problems, and often it has nothing to do with the ESP. They’re the bearer of bad news: You have questionable email tactics or poor data and, now you’re paying the price. That being said, if another ESP claims to show better performance than your current ESP, don’t immediately assume your current ESP is sharing inaccurate information or isn’t as “good” as the competitor. No ESP has “magic tools” or can guarantee you higher inbox performance. Instead, understanding not all ESPs are the same in their anti-spam policies, infrastructure setup, features and services, and reputation as a platform may lend their senders the opportunity to better manage deliverability.

“Your deliverability is in your hands, not your ESP’s,” stresses Luke Martinez, solutions architect at 250ok and former deliverability consultant at SendGrid.

And that’s all he’s got to say about that!

A competitor ESP offered a lower price than what we currently pay.
This is a reason many marketers switch, and while it’s up to you whether or not the risk outweighs the reward, changing ESPs is a complex and challenging process. It takes time, energy, planning, strategy, and diligence. It’s a lot like turning the shower on; unless you are a magician or a millionaire, you probably need to let cold water warm up to steamy-hot goodness. Unfortunately, it’s not as satisfying.

“Postmaster queues are about 20% ESP migration issue tickets on any given day,” says Sridhar Chandran, former AOL postmaster and current 250ok solutions architect.

Is your email program ready for a change? Do you have the time and energy to get it right before switching? Is rushing through all the prep work, facing potential migration issues, and then learning a new ESP’s nuance worth the price savings, if price is the only reason to switch?

Your call.

All that said, there are plenty of reasons to consider an ESP switch. These are some of the most reasonable explanations for starting the process:

Our current ESP doesn’t meet our scaling/changing needs.
Life happens, you know? If you’re lucky, your email program gets to grow year-over-year to accompany the astronomical success of your business. When this happens, it’s not uncommon to find your current ESP’s offerings less directly align with your needs, such as a lack of integrations or an absence of adequate customer or product support as you try new concepts or technologies, while another ESP can provide solutions closer to your needs. That’s OK!

We want to consolidate our marketing tech stack.
As the world of marketing automation and technology grows, so do your options. You no longer need to have several different contracts to do everything you want with your email program. Some ESPs offer bundled features and some provide an even more comprehensive set of tools as a customer data platform (CDP). For instance, you might move from a smaller ESP that only sends email to a robust marketing automation platform like Marketo, an Adobe company, which also houses customer data and more. Some CDPs partner with email delivery platforms themselves, but at the end of the day, you have plenty of options to consolidate multiple functions into one platform, and that could make your marketing efforts much easier.

Our ESP just isn’t the right fit.
At the end of the day, if your ESP isn’t providing what you need, you likely have a good case to switch. If you’re looking for richer data sets, more features, required integrations you lack, or the customer service leaves you lost or wanting more help, you have options to find a better fit for your business and your sanity.

Let’s not touch the process of finding the right ESP here, because we’ve already done this and because it’s a whole thing. Instead, let’s look at a stepped process to help you get the most out of the switch, leaving your organization in a better place and without switchers-remorse (is that a thing?).

Before the switch

  • Do an RFP process
    Okay, we promised we wouldn’t touch the buyer’s journey, but this is important. Make sure you understand what you need for your business and from your partners.
  • Audit your assets
    Understand what you’re working with: landing pages, email templates, data fields,
    unsubscribes, preference centers, the works. Know exactly what needs to be accounted for in the migration.
  • Do some projections
    By this point, you know this is an arduous process. Do you want to go through this again next year if your business booms and you outgrow your new ESP? Look at your organization’s growth projections, make some educated guesses about technologies you’ll want to use over the next few years, and confirm your future needs are well represented by the ESP of your choice.
  • Collect benchmarking data from current ESP
    This is especially important if you believe your email performance was tied to your ESP. Be sure to find your most valuable metrics, track your average for a set period before the switch, and be prepared to juxtapose them against the performance on the new ESP to see if there is a noticeable change.
  • Create a logical, reasonable migration plan
    No sugarcoating here—switching is not simple or easy. Don’t expect to be able to switch off your current ESP the day the contract ends. Expect to pay both services for a couple of months to ensure things are going according to plan. Manage your expectations up front, so no one is surprised when there is not a night-to-day transition of ESPs.


During the switch

  • Run concurrent ESP services for two to three months
    This is similar to what we just said, but for a different reason. Having concurrent services for a while better ensures you won’t have a full-blown dumpster fire if something doesn’t go according to plan. This also can serve as a back-up solution while you work out any potential kinks or tackle any unforeseen issues. It’s basically your “Oh shizz!” button.
  • Warm up everything
    Spend quality time warming up your IPs and your domains on the new ESP. This is where the split services comes in handy. You can ramp up sending on your new ESP with your most engaged subscribers while still sending from your old ESP, and feel more confident you won’t raise any mailbox providers’ (MBP) red flags with unusual sending behavior.


After the switch

  • Compare apples to apples when evaluating success
    Performance-switchers, we’re talking to you. This is where your pre-switch benchmarking data comes in clutch. Make sure you’re looking at the same performance indicators on your new ESP as you were on your old ESP. This is your opportunity to see where the ESPs differ and adjust accordingly to optimize for success on your new path.
  • Review the process and document pain points and wins
    Bad news: Some marketers do this process every two years. You’ll want to document all the things that went right, and everything that went not as right, to help ease this process the next time. Hindsight is 20/20, so pretend this is your chance to get ESP Lasik, and make sure you write down everything you wish you knew the first time to walk into the next switch eyes wide open.
  • Kick back and enjoy
    You did it. Yay!


Of course, every journey is different. Every organization’s reasoning varies, every marketer’s style is unique, and this guide is only meant to help oil the machine, not provide AI/machine-learning to automate it for you. We hope these topics give you food for thought before embarking what can be a long and arduous process. Once you’re ready, don’t forget about our buyer’s guide. Once you select your ESP, don’t forget, we work with virtually every ESP, so you can benefit from 250ok intelligence no matter which you choose (probably). Hit us up when you’re ready, and let us know if you have any questions. We’re here for you!

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