Changing your email service provider (ESP) is not a decision to take lightly. Businesses are extremely reliant on email for a wide mix of communications. And there are risks involved with switching your ESP. It takes time and resource. What’s more, it can also negatively impact results in both the short term and long term if not done correctly.

But if you’re not getting what you need from your existing email service provider, staying put could be even riskier.

If you’re still in two minds about making a switch, please read our guide on How to switch Email Service Provider. It contains plenty of advice on what to look for and what questions to ask when evaluating a new ESP.

If you have made your mind up and are ready to switch your email service provider, then read on.

Making your switch runs smoothly should be a top priority when you do decide to change your ESP. But breaking up is never easy. And because email is such an important channel, the process of leaving your current ESP can be particularly stressful. What’s more, switching ESP can cause email deliverability to tank if not done in the right way.

To help you mitigate the risks, we’ve put together a list of ten things to do when switching ESP. Following these steps will help safeguard your email deliverability and maintain a good sending reputation during the changeover.

1. Transfer your unsubscribe list

Before you make the switch, you need to gather several important lists of data from your existing ESP. First things first, make sure you have a list of unsubscribes. This helps you avoid making the mistake of sending to people who have already opted out.

2. Get a list of bounces

Next up, get a list of all of your hard and soft bounces. Continuing to send to these via your new ESP may have a negative impact on deliverability.

3. Transfer spam addresses

It is important to transfer the list of email addresses you’ve identified as spam traps when switching ESP. Your email marketing may be spam-free but you can still be penalized if you start sending to spam traps from your new ESP.

4. Clean your list

Switching ESP is the perfect time to clean your list. Who hasn’t opened an email this year? Now is the time to trim your list down to size. A smaller, more engaged list is good for deliverability.

5. Use engagement history

Your highly engaged subscribers are your secret weapon when switching ESP. Sending to this list first from your new IP address helps build your reputation as a sender. So, be sure to harvest your engagement history before switching.

6. Bring across sending domain

If your new ESP allows it, bring across your sending domain when switching. This is beneficial as you have built up your reputation on this domain. What’s more, you’ll already be added to your subscribers’ safe sender list — a win for deliverability!

7. IP certification

If you use an IP certification tool to improve deliverability, be sure to let them know you’re switching ESP. A quick task, but one that’s easily forgotten.

8. Gradually increase send volumes

Suddenly sending a large volume of emails from a new IP can lead to mail being rejected. This is because your Internet Service Provider (ISP) may view the activity as suspicious.

So, if you’re switching to a new dedicated IP, you’ll need to warm it up. IP warming is a process of gradually increasing send volumes over a number of days or weeks. This slowly builds up your sender reputation and improves deliverability.

9. Check bounce and blocked rates after each send

As you gradually increase your send volumes, keep checking the bounce and blocked rates after each send. Avoid increasing your volume if these are over 5 percent to protect your IP’s reputation.

10. Update sign-up forms

Make sure your sign-up forms are updated or redirected to reflect the change in ESP. Neglecting to do this could mean people are unable to join your mailing list. Conduct an audit to ensure every form is updated.


Switching ESP doesn’t have to be a disaster for your email deliverability. Following the ten steps we’ve explored will protect your reputation and ensure a smooth transition. If you’ve decided to switch ESP, we recommend choosing a company that will help you complete the tasks on our list — like us!

Pure360 works closely with clients to ensure their move to our platform is seamless and that deliverability doesn’t suffer. We have a tried-and-tested process in place to warm your dedicated IP and improve your experience. To see our email marketing platform in action, book your demo.

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