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Do I need to warm an email list when migrating email platforms?

In short, the answer is YES. A big capital letter, yes.

Switching to a new email platform can offer better features, improved usability, and more robust analytics, but it also presents a challenge that many businesses overlook: maintaining email deliverability. 

When you start sending emails from a new platform, your messages are sent from a new IP address, which Internet Service Providers (ISPs) do not recognise. This unfamiliarity can lead to your emails landing in the spam folder, drastically impacting your marketing efforts.

To avoid these pitfalls and ensure your messages reach your audience’s inboxes, it's crucial to warm up your email list—a process that gradually increases the volume of emails sent from your new platform. This strategic approach helps ISPs recognise and trust your new sending IP, enhancing overall deliverability and engagement rates. 

Below, we explore the detailed steps you need to take to effectively warm up your email list when migrating to a new email platform.

How to warm an email list when migrating platforms

1. Understand the Importance of IP Warming

When you move to a new email platform, you typically send emails from a new IP address. Internet Service Providers (ISPs) don't recognise this new IP and may treat emails sent from it as potential spam. Warming up the IP means gradually increasing the volume of emails sent from this new address so ISPs can recognise it as legitimate based on positive engagement metrics.

2. Segment Your Email List

Before you begin the warming process, segment your email list based on user engagement:

  • Highly Engaged: Users who frequently open and interact with your emails.

  • Moderately Engaged: Users who occasionally interact with your emails.

  • Low Engagement: Users who rarely open emails.

Start the warming process with your most engaged users because they are more likely to interact positively with your emails, sending strong positive signals to ISPs.

3. Plan Your Email Cadence

  • Start Small: Begin by sending emails to a small group of engaged recipients. Depending on your total list size, this could be as few as 10-40 emails per day. The general rule of thumb is to start no higher than 5-10% of your list size for this first send.

  • Gradually Increase Volume: Slowly increase the number of emails you send daily. For example, you might start with 20 emails on day one and increase by 10-20% each day, contingent on positive engagement and low bounce rates.

  • Use Consistent Sending Practices: Stick to consistent sending times and days to help ISPs recognise your sending patterns as legitimate.

4. Monitor Key Performance Indicators

Pay close attention to:

  • Deliverability Rates: Are your emails reaching the inbox?

  • Open Rates: Are recipients opening your emails?

  • Click-Through Rates: Are recipients engaging with the content?

  • Bounce Rates: How many emails are not being delivered?

  • Spam Complaints: Are recipients marking your emails as spam?

5. Ask for Whitelisting

Encourage your most engaged users to add your sending email address to their address books. This action significantly improves deliverability because it signals to email providers that the sender is trusted.

6. Adjust Based on Feedback and Metrics

Use the data you gather to refine your approach. Adjust your strategy if you notice issues with certain ISPs or specific segments showing lower engagement. This might include pausing increases, revising email content, or even segmenting your list differently.

7. Use Best Practices for Email Content

Ensure that your emails are well-crafted and relevant:

  • Personalisation: Use the recipient's name and other relevant data.

  • Valuable Content: Provide information that is useful to the recipient.

  • Clear Calls to Action: Make it easy for recipients to understand what you want them to do.

By carefully warming up your email list when switching platforms, you ensure the health of your sender reputation, maintain high deliverability rates, and continue engaging effectively with your audience.


Q: Why do I need to warm up my email list when migrating to a new platform?

A: Warming up your email list is crucial because it helps establish your new sending IP address as trustworthy with Internet Service Providers (ISPs). This gradual process helps avoid being marked as spam, ensuring your emails continue to reach your audience’s inboxes.

Q: How long does it take to warm up an email list?

A: The duration of the warm-up process can vary depending on the size of your email list and your previous engagement rates. Typically, it can take anywhere from a few weeks to a couple of months. The key is to start with small volumes and increase gradually as you monitor engagement and deliverability metrics.

Q: What are the consequences of not warming up an email list?

A: Failing to warm up your email list when migrating platforms can lead to high bounce rates, increased spam complaints, and poor deliverability. This can damage your sender reputation, making it difficult for your emails to reach the inbox even beyond the initial migration period.

Q: Can I warm up my email list by sending all types of emails?

A: It’s best to start the warming process with highly engaging content encouraging opens and clicks, such as newsletters or special promotions. These emails are more likely to generate positive engagement, which is critical in establishing a good sender reputation.

Q: What metrics should I monitor during the warm-up process?

A: Key metrics to monitor include deliverability rate, open rate, click-through rate, bounce rate, and spam complaint rate. These indicators will help you understand how well your emails are being received and whether adjustments are needed in your approach.

Q: How do I segment my email list for warming up?

A: Segment your list based on engagement levels. Start with your most engaged subscribers as they are more likely to interact positively with your emails. As your IP reputation builds, you can gradually include less engaged segments.

Q: What should I do if my emails start going to spam during the warming process?A: If you notice an increase in emails going to spam, pause the increase in volume and review your email content and list hygiene. Make sure your emails comply with best practices for email marketing and that your list does not contain outdated or incorrect email addresses.


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