What are the best practices for re-engaging inactive email subscribers safely?
Michael Ko
Co-founder & CEO, Suped
Published 20 Jun 2025
Updated 17 Aug 2025
7 min read
Re-engaging inactive email subscribers is a common challenge for many email marketers. On one hand, you want to reactivate potentially valuable contacts and maximize your list's reach. On the other, sending emails to unengaged recipients carries significant risks to your sender reputation and deliverability.
These risks include increased spam complaints, higher bounce rates, and potentially getting your IP address or domain placed on a blocklist (or blacklist). Mailbox providers like Google and Yahoo prioritize user engagement, and sending to disengaged users signals poor list management, which can lead to your emails landing in the spam folder, even for your active subscribers.
The key is to approach re-engagement strategically and cautiously, with a strong focus on maintaining a healthy sender reputation. This means understanding the current state of your inactive segments, carefully preparing your lists, crafting compelling messages, and diligently monitoring the results.
Identifying inactive subscribers and assessing risk
Before you even think about hitting 'send,' the first critical step is to accurately identify your inactive subscribers. Inactivity isn't always clear-cut, as it can be defined by various metrics and timeframes. Some consider 90 days of no opens or clicks to be inactive, while others might stretch that to six months or even a year, depending on their sending frequency and audience behavior.
It is important to segment your list based on engagement levels. Create distinct segments for highly engaged, moderately engaged, and inactive subscribers. For those who haven't opened or clicked in a significant period, it's wise to consider their status carefully. You might find some users who are still valuable, but simply aren't engaging with your current content.
Understanding how long subscribers have been inactive is crucial. The older the inactivity, the higher the risk associated with re-engagement. For very old or unmanaged lists, the presence of spam traps and invalid addresses can be substantial, posing a direct threat to your email deliverability. For more on this, consider reading about email list hygiene practices.
Risks of contacting truly inactive segments
Increased spam complaints: Unengaged recipients are more likely to mark your emails as spam, which directly harms your sender reputation.
Higher bounce rates: Over time, email addresses become invalid, leading to hard bounces that signal poor list quality.
Spam trap hits: Old, uncleaned lists are prone to containing spam traps, which are addresses used to identify spammers. Hitting one can lead to immediate blacklisting.
Lower inbox placement: ISPs will see low engagement and high complaints, filtering your emails to the spam folder for all subscribers, including active ones. This impacts overall email deliverability.
Preparing your list for re-engagement
Before initiating any re-engagement campaign, it's paramount to clean your list thoroughly. The older the inactive segment, the more vital this step becomes. This process involves identifying and removing invalid, non-existent, or high-risk email addresses from your list.
Email validation services can help you identify addresses that are likely to hard bounce or are known spam traps. While no service is 100% foolproof, using a reputable validator significantly reduces your risk. This proactive approach safeguards your sender reputation and helps avoid being placed on an email blocklist (or blacklist).
Consider how long the segment has been inactive. If it's been over two years, especially if the original permission was not explicit (e.g., single opt-in), you might find that the permission is no longer valid, as some regulations like GDPR have implications for data retention and consent. It might be safer to remove extremely stale contacts. You can learn more about best practices for unsubscribing inactive users.
Risks of neglecting list hygiene
Damaged sender reputation: High bounce rates and spam complaints flag you as a risky sender.
Reduced deliverability: Emails are more likely to land in spam folders or be rejected by ISPs.
Increased costs: Sending to invalid addresses wastes resources and marketing budget.
Legal and compliance issues: Continuing to email unsubscribed or invalid addresses can violate anti-spam laws.
Improved deliverability: Higher inbox placement for your re-engagement efforts and future campaigns.
More accurate metrics: Your engagement rates reflect a cleaner, more responsive audience.
Reduced spam trap hits: Minimizing contact with these dangerous addresses protects your domain from being blacklisted.
Designing effective re-engagement campaigns
Once your list is cleaned, it's time to craft your re-engagement message. These emails need to stand out and offer clear value to prompt a response. The goal isn't just to get an open, but to get a meaningful interaction, whether it's a click, an update to preferences, or even a direct reply.
Personalization is key, reminding subscribers of their past interaction or the value they once found in your emails. Consider offering an incentive, like an exclusive discount, early access to content, or an invitation to a special event. Keep the message concise and focused, with a clear call to action. For more ideas on how to craft these emails, check out this guide on re-engagement campaign strategies.
When sending, prioritize a gradual approach. Instead of a single blast, send your re-engagement emails in small batches over a few weeks. This allows you to monitor deliverability metrics closely and pause if you notice any negative trends, like an uptick in spam complaints or bounces. You should also consider using a dedicated sub-domain for re-engagement campaigns to isolate any potential negative impact from your primary sending domain.
Campaign element
Best practice for re-engagement
Subject line
Use compelling, direct, and curiosity-invoking phrases. Examples: "We miss you!", "Still want to hear from us?", "Your last chance."
Content
Personalize the message. Remind them of value. Offer an exclusive incentive or updated content. Ask a direct question about their preferences.
Call to action (CTA)
Make it clear and easy to take action. Options: "Click here to stay subscribed," "Update your preferences," "Visit our site."
Frequency
Send a series of 2-3 emails over a few days, not a single blast. Allow time for responses between sends. Some suggest 48-hour gaps.
Unsubscribe option
Provide an easy and clear way to unsubscribe. This is crucial for compliance and avoids spam complaints. See Mailgun's re-engagement guide.
Monitoring performance and managing outcomes
As your re-engagement campaign unfolds, continuous monitoring is non-negotiable. Pay close attention to your key performance indicators (KPIs), especially open rates, click-through rates, unsubscribe rates, and spam complaint rates for the specific segment you are targeting. A sudden spike in spam complaints or bounces is a red flag indicating that your re-engagement efforts might be negatively impacting your sender reputation. Monitoring your domain reputation is critical and you can use tools like DMARC monitoring for visibility.
For subscribers who respond to your re-engagement attempts, move them back into your active segments. This ensures they receive your regular content and helps reinforce their engagement. If they don't respond after the re-engagement series, it's generally best to suppress them. Continuing to send to them risks further damage to your reputation and provides no real marketing benefit.
Sunsetting (or purging) truly inactive subscribers is a healthy practice for your email program. While it might seem counterintuitive to remove contacts, a smaller, more engaged list performs better, yields more accurate data, and significantly improves your overall deliverability. This process also reduces the likelihood of hitting spam traps and ending up on a blocklist (or blacklist). Discover best practices for sunsetting inactive subscribers.
Maintaining a robust blocklist monitoring strategy helps you quickly detect if your re-engagement efforts have landed you in trouble. Immediate awareness allows for prompt action to mitigate damage and request delisting, protecting your domain's reputation for all future sends.
Example of inactivity segmentation logic
IF last_engagement_date < '2023-01-01' THEN 'Inactive - Pre-2023'
ELSE IF last_engagement_date < '2024-01-01' THEN 'Inactive - 2023'
ELSE 'Active'
Views from the trenches
Best practices
Always segment your inactive users by duration of inactivity before attempting re-engagement.
Utilize a robust email validation service to clean your inactive lists before sending any campaigns.
Consider using a separate sending subdomain for your re-engagement campaigns to isolate potential reputation risks.
Craft compelling, personalized content with a clear call to action and an easy unsubscribe option.
Send re-engagement campaigns in small, controlled batches to monitor performance and react quickly to issues.
Common pitfalls
Sending a re-engagement campaign to an entire, unsegmented inactive list in a single blast.
Failing to clean your list, leading to high bounce rates and spam trap hits.
Not providing a clear and easy way for subscribers to opt-out, resulting in spam complaints.
Ignoring negative metrics like increased spam complaints or blocklist listings during a campaign.
Continuing to email subscribers who show no interest after multiple re-engagement attempts.
Expert tips
Implement a consistent email list hygiene routine, not just before re-engagement campaigns.
A/B test different subject lines and content within your re-engagement series to optimize for engagement.
Automate the re-engagement process to ensure timely follow-ups and suppression of unresponsive contacts.
Focus on value proposition: remind subscribers what they're missing out on from your brand.
Analyze your data to understand typical inactivity cycles for your audience and adjust re-engagement timing accordingly.
Marketer view
A marketer from Email Geeks says they found that in Denmark, email permissions can expire after two years of no contact, making it invalid to send to them.
2023-09-01 - Email Geeks
Expert view
Expert steve589 from Email Geeks says assessing how stale a segment is, specifically the last contact date for each address, is crucial for planning re-engagement safely.
2023-09-01 - Email Geeks
Maximizing engagement while protecting your sender reputation
Safely re-engaging inactive email subscribers is a delicate balance between maximizing your audience and protecting your crucial sender reputation. It's not about forcing engagement, but rather providing a respectful, value-driven opportunity for dormant contacts to reconfirm their interest. By meticulously cleaning your list, segmenting strategically, and crafting compelling, personalized messages, you significantly increase your chances of success.
Remember, the goal is not just to send emails, but to ensure they reach the inbox of interested recipients. This protects your overall email deliverability and prevents issues like emails going to spam or your domain being placed on a blocklist. Continuous monitoring and a willingness to remove truly unengaged subscribers are vital for long-term email marketing health.
By following these best practices, you can approach re-engagement campaigns with confidence, potentially reactivating valuable subscribers while safeguarding your most important asset: your sender reputation. For more on improving your reputation, explore this guide on understanding your email domain reputation.
