How to Warm up Your IP When Switching Email Service Provider

Looking to switch to a new email service provider (ESP)?

Are scare stories about how this could impact deliverability putting you off?

If so, read on. This blog post is here to allay your fears.

While it’s true that changing ESP has the potential to reduce email deliverability, it is by no means inevitable. There are a number of precautions you can take to ensure the switchover goes smoothly.

One way to keep deliverability rates healthy while switching ESP is to warm up your new IP address. This blog post explains how you can use IP warming to protect your sender reputation and avoid having mail rejected.

What is IP warming?

IP warming is the process of slowly ramping up your email send volume when you switch to a new ESP with a dedicated IP address.

Why do you need to warm up your dedicated IP?

When you send emails, Internet Service Providers (ISPs) assess the reputation of the IP address you send them from. This assessment impacts your email deliverability.

An ISP’s assessment of your IP reputation can determine whether they deliver your email to your recipient’s inbox or their junk. Sometimes it results in your mail being rejected completely.

Switching to a new ESP means you’ll be sending emails from a new IP that ISPs have no record of. When an ISP spots a large volume of emails coming from an unfamiliar IP, they may see this as suspicious. This causes mail to be rejected and damages your reputation as a sender.

Starting small and gradually increasing the number of emails being sent helps to build up your reputation as a sender. This keeps your email deliverability healthy as you switch over to your new IP.

Further reading: How to Improve Email Deliverability

How to ensure IP warming is successful

Now you understand why IP warming is important. But what do you need to consider if you want to do it well? Here are our three top IP warming tips:

1. Being consistent

It is important to steadily increase your send volumes in small increments. ISPs are looking for consistency, so a gradual increase keeps them happy. Sudden spikes in send volume or large gaps between sends can damage your sender reputation.

2. Targeting active and engaged users

Response rates are another important factor when it comes to building your new IP’s reputation. So, start by targeting users who you know are active and engaged. You can harvest data on these segments from your old ESP before you switch over.

3. Checking bounce and blocked rates

As you gradually increase your volume, keep checking your bounce and blocked rates after each send. It’s important to monitor for negative results and avoid increasing your send volume if they occur.

Forging ahead when you are getting a lot of bounces and blocks could cause permanent damage to your sender reputation. As a guide, avoid increasing your volume if bounce or block rates are above 5 percent.

What if results start to decline?

If results do decline, don’t panic. Simply pause for a few days. After a short break in sending, send to a smaller segment — one that you’ve already established is highly engaged. Doing so will help to regain the ISPs’ trust in your sends.

Be aware that results can vary between ISPs during the IP warming process. If you find results from one ISP are particularly poor, create a segment for email addresses from this ISP. It is a good idea to ramp up send volumes more slowly for this segment to protect your reputation.

What to do after your IP is warmed

Once you’ve finished warming your IP, it’s time to consider how to protect your sender reputation in the long term. Engagement is a major factor in this. Segmenting your audience according to engagement levels is a smart approach. You can personalise your message to resonate with each segment in order to improve engagement.

Further reading: 10 Things to do When Switching Your Email Service Provider


Switching ESP doesn’t have to lead to mail getting rejecting. IP warming is an important process which will rebuild your reputation as a sender and ensure a smooth transition. If you’ve decided to switch ESP, we recommend choosing a company that has a tried-and-tested IP warming process in place.

Pure360 can provide you with an IP warming plan tailored to your exact requirements. We will support your success by monitoring results and suggesting ways to improve. To see our email marketing platform in action, book your demo via the demo below.

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