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How to Re-Engage and Warm Up a Cold Email List

Understanding Cold Email Lists

An email list becomes 'cold' when the engagement levels (opens, clicks, responses) drop significantly. This often occurs due to a lapse in communication or when the content no longer aligns with the subscriber's interests. A cold list can decrease email deliverability and affect your overall email marketing performance.

Why you should warm your list

Warming a list will help ISPs trust your sending IP, enhancing overall deliverability and engagement rates. 

Key Summary

  • Initial steps to ensure your email list is in tip-top shape

  • Craft a re-engagement campaign

  • How to run a warming campaign

  • FAQs

The Initial Steps to Warming Up

Warming up a cold email list involves a strategic approach to re-engage subscribers who have not interacted with your emails over an extended period. Here’s a detailed step-by-step checklist to effectively start the process:

  1. Evaluate Your Email List

    1. Assess Engagement: Identify subscribers who haven’t opened or clicked through emails in the last 6-12 months, as this will help set up your send order once you begin.

  2. Clean Up Your Email List

    1. Remove Invalid Emails: Eliminate non-existent or error-prone email addresses that bounce back. Some platforms have this built into their offerings, but if not, check for incorrectly entered emails, i.e. obvious misspellings and multiple soft bounces. 

    2. Unsubscribe Low-Quality Contacts: Consider removing subscribers who have never engaged with your emails from the beginning, as they might affect your deliverability.

  3. Segment Your List

    1. Behaviour-Based Segments: Create segments based on past purchase behaviour, email activity, and preferences. This and previous open behaviour will set up your send order when you begin to warm. 

    2. Demographic Segments: Utilise demographic information to personalise re-engagement efforts. For example, you can tie the messaging to welcoming them back if they are a previous purchaser.

  4. Set Realistic Goals for Re-engagement

    1. Define Success Metrics: Establish what successful re-engagement looks like.

      1. A general rule of thumb is an open rate of 20% or higher. Any click-through is a bonus during this process.

    2. Adjust Expectations: Understand that not all inactive subscribers will re-engage, and focus on those who show potential interest.

  5. Prepare for Initial Re-engagement

    1. Craft Compelling Content: Develop content that addresses why subscribers may have disengaged.

    2. Offer Incentives: Include special offers, exclusive content, or access to new products as incentives to re-engage.

  6. Plan the Timing and Frequency

    1. Optimal Timing: Determine the best time to send re-engagement emails based on previous engagement patterns.

    2. Frequency Settings: Decide how many re-engagement attempts will be made before considering a subscriber genuinely inactive.

Crafting the Perfect Re-Engagement Campaign

Re-engagement campaigns should remind your subscribers why they signed up in the first place. Include:

  • Reintroduce your brand

  • A clear, engaging subject line.

  • A personal touch, addressing the subscriber by name.

  • A call-to-action that encourages interaction, i.e. a survey, offer, or a request to update preferences.

Now we warm!

When warming up an email list, especially after moving platforms, it's crucial to start with a smaller number of emails and gradually increase the volume over time to improve deliverability and reduce the risk of being flagged as spam. Here are some general guidelines:

  1. Segment Your List: Based on your segmenting above, first, choose recipients who have engaged with your emails in the past. This means selecting those who have recently opened, clicked through or purchased through your emails.

  2. 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 at most 10% of your list size for this first send.

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

  4. Monitor Responses and Adjustments: Pay close attention to key metrics such as open rates, click rates, bounce rates, and spam complaints. If you notice issues, pause or reduce the increase in volume to troubleshoot.

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

  6. Feedback and Adaptation: Adjust your strategy based on the feedback you receive from email service providers and the behaviour of your list's recipients.

Typically, the warm-up process can take anywhere from a few weeks to a couple of months, depending on the size of your list and your industry. The key is to be patient and take your time with the process, which can harm your long-term deliverability.


When should I warm a cold email list?

You should begin warming a cold email list as soon as you notice a drop in engagement rates. However, it's particularly crucial to revitalise your list before launching major campaigns, seasonal promotions, or when introducing new products or services. Regularly scheduled re-engagement efforts every 6 to 12 months can also help maintain a healthy and responsive email list.

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

It is advisable to warm up your email list when transitioning to a new email platform. Read more about that process here.

What if my re-engagement efforts fail?

Subscribers who remain disengaged after several attempts might need to be removed from your list to improve your deliverability and engagement rates.

What incentives can I offer to re-engage subscribers?

Consider offering exclusive discounts, early access to new products, or valuable content such as free guides or webinars that are relevant to their interests. Read more about effective re-engagement offers here. (Link to blog)

How do I personalise re-engagement emails effectively?

Utilise data like past purchase history, browsing behaviour, and previous email interactions to tailor messages that resonate with each subscriber's preferences and behaviours.

Can I use automation for re-engagement campaigns?

Absolutely. Automation tools can help you trigger re-engagement emails based on specific subscriber behaviours, such as a period of inactivity or a birthday.

Is it important to update my email list regularly?

Yes, regularly cleaning your email list to remove inactive subscribers and incorrect email addresses helps maintain a healthy sender reputation and improves engagement metrics.

This guide is written by Hedgehog, a Done With You digital marketing consultancy specialising in small and medium businesses in Australia. We offer digital marketing consulting, coaching, and training.


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