No two migrations are the same: How Mailgun helps migrate clients the right way

As an onboarding specialist at Mailgun, I’ve seen every type of migration from the ultra-streamlined to the large and complex. Whether you’re migrating from a legacy provider, other platform, or an in-house tool, one thing’s always true: A great migration isn’t just technical. It’s strategic.

The good news? That’s exactly what we specialize in. Here’s what to expect when making the switch to Mailgun and how we help you get it right from day one.

If you’re thinking about moving your email sending to Mailgun, you’re probably wondering what the process really looks like. As someone who’s helped dozens of companies big and small through this process, I can tell you it’s never exactly the same twice.

But there are some consistent truths. The companies that migrate smoothly are the ones who start with a plan, ask the right questions, and work closely with us to get it right. Here are my top five tips for migration prep:

1. Set expectations internally and externally. If you’re a martech offering sending services to your own customers, it’s on you to implement limitations and rules that protect your sender reputation. We’ll help you build those expectations into your platform and processes. This includes helping you answer the question: “What does it mean to maintain a good reputation on Mailgun?”
2. Plan account configuration and access early. Will your customers manage their own email activity, or will you do it for them? Will they need login access? Who’s creating sending domains? These aren’t small decisions, but they shape your long-term flexibility and scalability.
3. Understand your technical constraints. Can you migrate a few customers at a time? Or will it be a full-platform flip? One question I bet you’re not asking is will it work? Migration solves the problem of how it will work. That’s where our planning comes in.
4. Make sure you’re compliant. We’ll walk through opt-in processes, privacy policy requirements, and content guidelines. You’ll need a suppression list ready to import and a clear understanding of your current list hygiene practices.
5. Know what resources you’re bringing. Your internal bandwidth makes a big difference. We’ve worked with one-person teams who needed 8–10 weeks to migrate. At the other end of the spectrum with larger assets, the process can take 4–5 months, thanks to redundant systems and deep testing requirements.

Migration is always about management. Sometimes that’s management of expectations, sometimes management of users, but mostly it’s a combination of many factors.

For example, martechs are responsible for their behavior on the platform, and that includes the sending reputations of the customers under their umbrella; their sending practices, their list quality, and whether or not they follow basic email standards.

Too often I’ve seen martech clients open up their email platform with little oversight. They don’t vet their users or communicate the rules. That creates major problems for their sender reputation.

One of the first things we’ll do is help you build a clear framework for your users, including usage limits, sending policies, and guidance you can pass along.

One client, for example, needed a way to safely onboard their own customers to Mailgun. We worked with their team to build a customized onboarding flow, internal training, and a strategy focused on long-term reputation health.

These are the types of things we’ll ask you to be ready to talk about:

• What kind of emails are you sending? Transactional messages like password resets are different than marketing campaigns. How are you breaking down your sending, what are your needs?
• Do you have a website, privacy policy, and documented opt-in process? Security is a big deal for us, and so is compliance. When we migrate customers we make sure our policies align to protect the reputation of all our senders.
• Can you import a suppression list? In other words, are your tracking who you shouldn’t be sending too?
• Do you know your current engagement rates? Opens, clicks, bounces, unsubscribes – if you’re not tracking this already, we’ll help you set a baseline. But coming in blind makes it hard to compare performance post-migration.
• How do you maintain list hygiene?Are you cleaning out unengaged contacts? Do you have a sunset policy? Healthy lists are the foundation of good deliverability, and we’ll want to know how you manage yours.

These basics help us avoid surprises later. If someone tells us during a compliance review that they’re purchasing lists, or that they don’t have any engagement data, we know there’s work to do.

Even experienced teams get caught off guard by these:

• Customer behavior and reputation risks: If your clients send emails through your platform, you own the reputation. Too many forget this. We recommend best practices for dashboard rules, customer onboarding documentation, and usage limits-helping you establish safeguards to keep your domains protected.
• Purchased lists: Don’t buy an email list. Like seriously, not ever. If you’re managing email sends for clients and suspect they have purchased a list, we can advise on how to safely continue sending.
• No engagement tracking: Metrics matter, and they can tell us a lot about how to best set up your email program. Having zero metrics isn’t a deal-breaker but it’s sometimes a red flag.
• Outdated or nonexistent list hygiene: If you’re not actively monitoring these things now, we’ll help you get there before your first email hits send.

A couple of years ago we migrated a large client. They needed help creating onboarding processes for their own users. We partnered with them to build a system that mirrored our own onboarding framework complete with documentation, compliance guidance, and a customized reputation strategy.

That’s a level of strategic support you won’t find with other providers. Martech platforms often have a revolving door of support reps. With Mailgun, you get a dedicated onboarding specialist followed by your long-term Technical Account Manager (TAM). Enterprise plans also include a Technical Account Manager (TAM) and a dedicated backup.

We’ll help you determine a realistic migration timeline based on your resources and your warm-up needs.

Want to warm up IPs gradually while siphoning traffic? (The answer is yes, you do want to warm up your IPs.) We’ll create a phased approach. Need to switch everything over at once? We’ll still help you safeguard your deliverability.

Here’s a rough comparison to give you an idea (but it’s just a ballpark, every migration is different):

It’s not about how fast you move, it’s about whether you’re hitting the right steps.

It’s a message we emphasize often because it’s easy to overlook. Sending email isn’t the same as delivering email and the difference shows up in your results. Mailgun gives you the tools to manage that difference. And our onboarding process ensures you know how to use them from the start.

Once you’re live, support doesn’t stop.

• Core clients: Monthly touchpoints available
• Enhanced plans: Bi-weekly syncs
• Enterprise clients: Weekly meetings and reports

Your onboarding specialist and TAM continue to monitor your account and guide your progress while you settle in.

Thinking about migrating? Let’s talk. We’re here to ask the tough questions, flag the red flags, and help you build a plan that actually works.

Author: Casey Gurbanov Onboarding Specialist II, Sinch Mailgun