Switching from one email service provider (ESP) to another is one of those jobs that’s easy to underestimate. Depending on the size and complexity of your lists, it can take weeks, and the biggest risk isn’t losing data, it’s damaging your deliverability on the way over. Work through this list and you’ll avoid most of the problems.

1. Check Your Mindset

Yes, switching your email provider can be anxiety-inducing. But it’s also a good opportunity to take an honest look at your email strategy, from the big picture down to the small details. Now’s the time to simplify your processes, pinpoint what’s working and what’s failing, and see your new ESP as a fresh slate on which to build an email strategy that’s even more effective than your current one.

2. Clean your Account

There is no point re-creating a sub-optimal strategy in your new ESP. So, before exporting anything, go through your entire account, and remove anything that’s no longer needed. Those old tags and custom fields that you no longer use? Delete them. Too many segments? Merge them. Do what you can to simplify your account, as this will make the switching email service providers a whole lot easier.

3. Clean Your List

To keep deliverability high, you must avoid importing too many inactive subscribers to your new ESP. So before making the switch, run a reactivation campaign for anyone who hasn’t engaged in 6–12 months. Judge it on clicks rather than opens, since Apple Mail Privacy Protection makes a lot of opens automatic. When it’s over, remove anyone still inactive. They aren’t doing your list any favors, and they’re a real risk on a new platform with no sending history.

4. Record How Your Account is Organized

Write out exactly how your account is organized, so you have a list of everything that needs recreating during your migration. We’re talking about:

  • The names and specific settings of each list/campaign
  • Tags and custom fields
  • Segmentation rules
  • Sign-up sources and locations (i.e. sign-up forms and 3rd party sources)
  • The order of autoresponder sequences
  • Marketing automation conditions and settings
  • Landing pages
  • Reports
  • API Integrations
  • Users and permissions

And anything else that’s relevant to your email strategy.

5. Backup Anything Important

Download a copy of anything important (don’t worry about lists and stats for now, that comes later). Ensure you have a copy of all of your confirmation emails, email templates, autoresponders (both HTML and TXT versions), automation messages, landing pages, forms, hosted images and even your email archive, if possible.

6. Get to Know Your New ESP

Many ESPs offer free accounts, so sign up and take a good look around. Think about exactly how you’re going to organize your new account on this new platform, and the best approach to take. Watch and read tutorials in the help section of your new ESP. Become familiar with any new terminology. And message their support if you have any additional questions, such as any best practices you should be aware of to protect your deliverability.

7. Re-Read Your Contract

Ensure you know exactly what you’re signing up for. Look out for subscriber limits, send limits, exit clauses. Check how much notice you need to give to cancel your account. See how much notice the ESP must give you before increasing prices. Double check you’re getting all of the features you need.

8. Check Your HTML Email Works

If you use a custom HTML email template, send yourself a test email from your new ESP to ensure everything appears correctly. Check this on both desktop and mobile, and within various email clients. If there are any issues, you may have to re-write some of your template’s code before switching email providers.

9. Start Warming Your IP Address

If you’re moving to a dedicated IP address, work with your new ESP to start warming it up early. A new IP has no reputation, so volume has to be built up gradually over a few weeks, starting with your most engaged readers. Wait for your ESP’s go-ahead before sending full campaigns. If you’re on a shared IP, the ESP has already done this, so it isn’t something to worry about.

10. Check Your Sender Reputation

Keep an eye on your reputation before, during and after the move, so you spot problems straight away. Google Postmaster Tools is the most useful free view for Gmail: watch your spam rate and delivery errors in particular. If either starts climbing, slow down before the problem gets worse.

11. Inform IP Certification Tools

If you use any IP certification tools, inform them that you will be changing your ESP so they are aware. This will help to protect your list from any drop in deliverability.

12. Set Up What You Can on Your ESP

Now’s the time to set up everything you can on your new account. Recreate autoresponders, automations, confirmation messages, etc. Recreate your landing pages, and sign-up forms, too. Depending on your ESP, this may also be the stage where you set up your new lists/groups, or create any new custom fields.

13. Export Stats and Reports

If possible, export a copy of your campaign statistics from your current ESP so you have this as a reference. It’s recommended to do this just before you start migrating your email lists over to your new account, as this will ensure the stats are as up to date as possible.

14. Import Bounce and Unsubscribe Lists

Export bounce, unsubscribe, and spam complaint lists from your current ESP, then add these to a suppression list in your new ESP. This is important, as it ensures that you don’t mistakenly send emails to people who have previously unsubscribed, or to addresses which cause emails to bounce. Do not skip this step.

15. Start With Your Most Active Subscribers

To help maintain your sender reputation, you should always migrate your most active subscribers first. When you import these subscribers, go over everything with a fine tooth-comb, and check that everything is set up properly before sending any emails. Check that any tags and custom fields are imported correctly. Ensure your subscribers are added to the correct segments and groups. Double check that subscribe data is also accurately imported (this is especially important for subscribers from the EU, as you must comply with GDPR rules).

16. Set Up Domain Authentication

Do this before you send anything. Set up DKIM on your own domain at the new ESP, plus a custom return-path if they offer one, and make sure your DMARC record still passes with the new service. Gmail and Yahoo have required SPF, DKIM and DMARC from bulk senders since February 2024, and Microsoft brought in the same rules for Outlook.com in May 2025, so a gap here can mean mail gets rejected rather than just filtered.

Don’t remove your old ESP’s DNS records until you’ve completely finished sending from it.

17. Keep the Same Sending Domain

Your reputation lives mostly with your sending domain, the one in your From address, and that’s yours, not the ESP’s. Keep sending from the same domain on the new platform and your history comes with you. Set up a custom tracking domain on the new ESP too if you had one before. Changing your sending domain at the same time as your ESP throws that history away, so avoid doing both at once.

18. Increase Send Volume Gradually

Only when you’re ready, start sending campaigns to a small volume of subscribers. This precaution allows you to notice any deliverability issues before they become irreparable. For example, if your bounce rate jumps, your spam complaint rate gets anywhere near Gmail and Yahoo’s 0.3% limit, or Gmail starts deferring your mail, don’t increase the volume. Something needs fixing first. The same goes for clicks that fall well below what you’re used to. If everything looks ok after sending a few more campaigns, migrate more of your subscribers over to the new ESP. Keep doing this until all of your subscribers are in their new home. This could take a few weeks or even a few months, depending on the size of your list.

19. Keep a Close Eye on The Stats

As you gradually move your entire list over to your new ESP, keep a close eye on the stats and look out for anything untoward. If anything catches your attention, speak to your ESP straight away about possible issues and recommended remedies.

Taken step by step, switching email providers needn’t be as daunting as it sounds. But it should still be done with care. As mentioned, this is the perfect time to reassess your email strategy and the overall organization of your account. So take this time to make it as efficient as possible.

Once the switch is complete, which can take up to a few months for a big or complicated list, you can get back to the more interesting work of growing the newsletter.