How to manage deliverability when re-engaging inactive email subscribers?
Matthew Whittaker
Co-founder & CTO, Suped
Published 20 Jun 2025
Updated 19 Aug 2025
7 min read
Re-engaging inactive email subscribers is a critical task for any email marketer. While the allure of a larger list is strong, sending emails to unengaged contacts can significantly harm your email deliverability and sender reputation. It is a delicate balance, requiring careful planning and execution to avoid landing in the spam folder or on an email blocklist (or blacklist).
The primary goal is to re-ignite engagement without triggering spam filters or alienating recipients further. This means understanding the risks involved, meticulously segmenting your audience, and crafting highly targeted campaigns designed to elicit a positive response. Neglecting these steps can lead to severe consequences for your email program.
In this guide, I will walk you through the essential strategies for managing deliverability when attempting to re-engage inactive subscribers. My focus is on practical steps that protect your sender reputation while giving you the best chance to win back valuable contacts.
Defining and segmenting inactive subscribers
Before you even think about hitting send, you need a clear definition of what constitutes an inactive subscriber. This definition often varies by business and email frequency, but it typically involves a lack of opens or clicks over a defined period. For some, it might be 90 days, for others, it could be six months or even a year.
Once you have your definition, segment these inactive contacts into their own group. This is crucial for controlling the volume of emails sent to them and for monitoring their response separately. Avoid mixing them with your highly engaged audience, as their low engagement metrics can drag down your overall sender reputation and make it harder to deliver emails even to your active users. You can learn more about how to manage inactive email subscribers to improve Gmail deliverability.
A granular approach to segmentation is highly recommended. You might consider segmenting based on how long they have been inactive (e.g., 90-180 days, 181-365 days, 365+ days) or by their last activity (e.g., last purchase, last website visit). This allows for a more tailored re-engagement strategy, as different levels of inactivity might require different approaches.
The risks of re-engaging inactive subscribers
Sending emails to inactive subscribers carries inherent risks to your email deliverability. Internet Service Providers (ISPs) like Google and Yahoo closely monitor engagement. Low open rates, high bounce rates, and increased spam complaints from re-engagement campaigns can signal to ISPs that your emails are unwanted, leading to lower inbox placement across your entire list.
One of the biggest dangers is hitting spam traps. These are email addresses repurposed by ISPs to catch senders with poor list hygiene. Sending to a spam trap can immediately land your domain or IP on a blocklist (or blacklist), severely impacting your ability to reach the inbox. This is why list validation is a critical first step.
Another concern is the potential for increased unsubscribes. While some unsubscribes are inevitable, a sudden surge during a re-engagement campaign can negatively affect your sender reputation. It indicates that your content is not relevant or that recipients feel trapped. It's better to have a smaller, highly engaged list than a large, disengaged one that hurts your overall deliverability, as discussed by Webbula in their blog on inactive subscribers.
Risks
Reputation damage: High spam complaints and low engagement decrease your sender score.
Blocklisting: Hitting spam traps or excessive complaints can lead to being added to a blocklist (or blacklist).
Wasted resources: Sending emails to non-responsive contacts wastes sending volume and budget.
Benefits
Improved metrics: Successful re-engagement can boost open and click rates.
List health: Reactivated subscribers contribute positively to your sender reputation.
Increased ROI: Winning back existing customers is often more cost-effective than acquiring new ones.
Crafting your re-engagement strategy
A successful re-engagement campaign is methodical and respectful of the subscriber's prior inactivity. The first crucial step, after segmentation, is list validation. Run your inactive segments through a reputable email validation service. This helps identify and remove invalid, non-existent, or spam trap email addresses, significantly reducing your bounce rate and protecting your sender reputation. If you're wondering when you should stop sending to inactive subscribers, validation is a key indicator.
Once cleaned, send your re-engagement campaign in small batches (a process often called warming up or gradual re-introduction). Start with the most recently inactive segment. Monitor your metrics closely after each send. If engagement is positive and spam complaints are low, you can gradually increase the volume or move to older segments. This strategic rollout prevents sudden spikes in negative metrics that could flag your sending practices.
Content is key in re-engagement. Your emails should be concise, compelling, and offer a clear value proposition. Remind subscribers why they initially joined your list and what they've been missing. Personalization can significantly improve response rates. Offer incentives, exclusive content, or options to update their preferences, such as email frequency or content types. Make it easy for them to take action or opt-out, as a clean unsubscribe is always better than a spam complaint.
Content strategy
Tailor your re-engagement messages to the specific segment of inactive subscribers. Acknowledge their absence and offer a compelling reason to return. This could be a special discount, new product updates, or exclusive content they might have missed. Make sure your call to action is clear and easy to find, prompting them to re-engage or update preferences.
Offer choices
Give subscribers options. Instead of just an unsubscribe link, provide a preference center where they can choose to receive emails less frequently, or select specific topics of interest. This empowers them to control their inbox experience, increasing the likelihood of re-engagement rather than a complete opt-out. As seen in Iterable's re-engagement best practices, this approach yields better results.
Monitoring and maintaining deliverability
Continuous monitoring is essential when re-engaging inactive subscribers. Pay close attention to your sender reputation metrics, including open rates, click-through rates, unsubscribe rates, and especially spam complaint rates. Tools like Google Postmaster Tools provide valuable insights into your domain's health and can alert you to potential issues.
If you notice a significant drop in deliverability, an increase in bounces, or a rise in spam complaints, it's a clear sign to pause your re-engagement efforts for that segment. Sending to a list that is generating high complaints will only further damage your reputation and may lead to being listed on a blocklist (or blacklist). Understanding why your emails fail is key to recovery.
Implement a clear sunset policy for subscribers who do not respond to re-engagement efforts. If they remain inactive after a series of targeted emails, it's best to remove them from your active mailing list. While it might seem counterintuitive to shrink your list, it's a proactive step to maintain high deliverability and ensures your engagement metrics reflect your true active audience. This is crucial for your long-term sender health.
The path to a healthier, more engaged list
Successfully re-engaging inactive email subscribers is a nuanced process that demands strategic planning and vigilant monitoring. By defining inactivity, segmenting your audience, validating your lists, and crafting compelling content sent in a controlled manner, you can maximize your chances of success while safeguarding your sender reputation.
Remember, the health of your email list is paramount to your overall email marketing success. Prioritize deliverability by adhering to best practices, continuously monitoring your performance, and being prepared to sunset contacts who no longer wish to engage. A smaller, engaged list is always more valuable than a large, unengaged one that puts your entire sending program at risk.
Views from the trenches
Best practices
Always segment inactive subscribers before re-engagement campaigns to avoid harming your overall sender reputation and metrics.
Utilize a reputable email validation service on inactive lists to remove spam traps, hard bounces, and invalid addresses before sending.
Implement a gradual warm-up strategy when sending to re-engaged segments, increasing volume slowly while monitoring performance.
Provide clear, compelling calls to action and easy ways to update preferences or unsubscribe in every re-engagement email.
Establish a clear sunset policy to remove subscribers who don't re-engage after multiple attempts, maintaining list hygiene.
Common pitfalls
Releasing large batches of inactive contacts back into your main segmentation all at once, leading to a sudden decline in engagement metrics.
Failing to segment inactive users, making it impossible to track their performance or understand the impact on overall deliverability.
Ignoring signs of declining deliverability (e.g., increased bounce rates, spam complaints) during re-engagement efforts.
Not getting internal buy-in or documenting the risks when management insists on re-engaging a large, uncleaned inactive list.
Believing deliverability issues are
Expert tips
Document every decision and change related to re-engagement campaigns, especially if you advise against a specific strategy.
Take daily snapshots of your deliverability metrics to track the impact of re-engaging inactive segments over time.
Segment inactive users based on activity level (e.g., 90-180 days, 180+ days) to tailor re-engagement approaches.
Focus on proving the negative impact of re-engaging uncleaned lists through data and performance charts.
Understand that deliverability directly impacts the bottom line, even if it's not immediately apparent to management.
Marketer view
Marketer from Email Geeks says to avoid adding all inactive contacts at once. You should try to add them back in slowly over time to mitigate risk.
2019-01-17 - Email Geeks
Marketer view
Marketer from Email Geeks says that if you must reintegrate inactive subscribers, segment them clearly. This allows you to show their performance compared to more engaged audiences and demonstrate any decline.
Google and 
Yahoo closely monitor engagement. Low open rates, high bounce rates, and increased spam complaints from re-engagement campaigns can signal to ISPs that your emails are unwanted, leading to lower inbox placement across your entire list.
Google Postmaster Tools provide valuable insights into your domain's health and can alert you to potential issues.
