What strategies should email marketers use for inactive subscribers, especially those with proxy opens?
Michael Ko
Co-founder & CEO, Suped
Published 15 Apr 2025
Updated 18 Aug 2025
9 min read
Managing inactive subscribers has always been a critical aspect of email marketing, but the landscape has become more complex with the prevalence of proxy opens. These automated 'opens', largely driven by features like Apple Mail Privacy Protection, obscure true engagement metrics. It's no longer enough to look solely at open rates, as they can be significantly inflated by bots and pre-fetching services. The real challenge now is discerning genuine human interaction from these programmatic signals, especially when deciding which subscribers to keep on your list and how to effectively re-engage them.
Our approach to inactive subscribers must evolve beyond simple open rate analysis. While opens were once a primary indicator, they now serve more as a vanity metric due to proxy activities. This shift necessitates a deeper dive into other engagement signals, like clicks, conversions, and even website activity, to get a clearer picture of subscriber intent. The goal is to maintain a healthy email list that drives actual value, rather than one filled with addresses that appear active but contribute nothing to your marketing objectives or sender reputation.
Defining inactive subscribers beyond opens
Defining inactivity in the current email ecosystem requires a multi-faceted approach. We can no longer rely on a simple 'no opens in X days' rule. Proxy opens mean that a subscriber might appear to be opening your emails, yet they are not actually seeing or interacting with your content. This false positive can skew your data and lead you to believe your campaigns are performing better than they are.
Instead, we should prioritize metrics that definitively indicate human engagement. Clicks are a strong indicator, as they usually require a conscious action from the subscriber. However, it is important to note that even clicks can sometimes be influenced by bot activity, although this is less common than with opens. Other valuable signals include website visits originating from email, purchases, or interactions with customer service.
To effectively manage this, segment your audience based on a combination of these engagement signals. Create tiers of inactivity, moving subscribers through a lifecycle that attempts to re-engage them with progressively more targeted content. For instance, distinguish between those with no engagement at all, those with only proxy opens, and those who open but never click. This segmentation allows for more nuanced and effective strategies.
Understanding this distinction is crucial for accurate list hygiene and maintaining a positive sender reputation. Sending to a large segment of subscribers who only generate proxy opens, without any actual interaction, can signal to Internet Service Providers (ISPs) that your emails are not valuable or desired. This can negatively impact your deliverability to genuinely engaged subscribers as well.
The impact of inactive subscribers on deliverability
Continuing to send emails to a significant portion of inactive subscribers, particularly those primarily generating proxy opens, can severely damage your deliverability and overall inbox placement. ISPs are sophisticated and analyze a multitude of engagement signals to determine where your emails should land. If your emails are consistently 'opened' by bots but rarely clicked or interacted with by humans, it sends a strong signal that your content isn't relevant or desired.
This lack of genuine engagement can lead to lower sender scores, increased likelihood of landing in the spam folder, and even getting your IP or domain placed on a blacklist (or blocklist). ISPs use various algorithms to detect engagement patterns, and a high volume of proxy opens without corresponding clicks or other positive interactions can be flagged as suspicious. They might interpret this as an attempt to game the system or as an indication that your list contains a high percentage of low-quality or inactive addresses.
The risk of hitting spam traps also increases when you continue to email inactive segments. Spam traps are email addresses used by ISPs to identify spammers. They are often recycled addresses that have become inactive, or pristine addresses created solely for trapping spammers. Sending to these addresses, even unintentionally, can instantly flag you as a sender of unsolicited mail, severely damaging your reputation and deliverability.
Maintaining a clean and engaged list is paramount for long-term email marketing success. By proactively identifying and addressing truly inactive subscribers, you reduce the risk of negative sender reputation impacts and ensure your emails reach the inboxes of those who genuinely want to receive them. This proactive approach improves your overall deliverability and the return on investment for your email campaigns.
Effective re-engagement strategies
When addressing inactive subscribers, particularly those with proxy opens, a targeted re-engagement strategy is essential. The goal isn't just to get them to open an email, but to encourage meaningful interaction. Start by segmenting these subscribers based on their last genuine engagement, not just their last recorded 'open'. You can explore more on re-engagement campaign strategies.
Consider a multi-channel approach beyond email. If a subscriber isn't engaging with your emails, perhaps they'll respond to an ad on social media or a direct mail piece. The aim is to remind them of the value you offer and prompt them to re-engage with your brand, potentially even updating their email preferences or providing a different contact method.
Open-based segmentation (outdated)
Reliability: Highly unreliable due to proxy opens (e.g., Apple Mail Privacy Protection, Gmail pre-fetching).
True Engagement: Does not accurately reflect if a human saw or interacted with the email.
Deliverability Impact: Continuing to send to 'open-only' inactives can negatively affect sender reputation and inbox placement.
Click-based segmentation (recommended)
Reliability: Much more reliable as it requires explicit user action.
Deliverability Impact: Focusing on click-engaged subscribers improves your list health and signals positive engagement to ISPs.
When crafting re-engagement emails, focus on clear value propositions and a single, compelling call to action. Make it easy for subscribers to confirm their interest, update preferences, or opt-out. For example, a simple button asking, "Yes, I want to keep receiving emails", can be very effective. This also provides an opportunity to gather fresh consent, which is particularly important for list hygiene purposes.
When to sunset (remove) inactive subscribers
Knowing when to sunset (remove) inactive subscribers is just as important as trying to re-engage them. Holding onto inactive addresses, especially those showing only proxy opens, can significantly harm your sender reputation and inflate your subscriber count with unengaged users. This practice can lead to lower inbox placement rates and potentially trigger spam complaints from users who never intended to receive your emails.
The cutoff point for sunsetting will vary by business and email frequency, but a common practice is to remove subscribers who haven't shown any genuine engagement (clicks, website visits, purchases, etc.) in 6-12 months, after a dedicated re-engagement campaign. It's crucial to distinguish between real human inactivity and proxy opens. You can gain more insights into sunsetting practices to improve deliverability.
Before removing them, ensure you've made a final, clear attempt to confirm their interest. This might be a reactivation campaign with a strong call to action. If they still don't engage, it's a clear signal that they are no longer interested, and keeping them on your list becomes a liability rather than an asset. Remember, a smaller, highly engaged list is far more valuable than a large list with many inactive contacts.
Best practices for list hygiene
Regularly clean your email list to remove unengaged subscribers and prevent deliverability issues. This includes those with consistent proxy opens but no clicks.
Segment aggressively: Create segments for different levels of engagement, especially distinguishing actual clicks from proxy opens.
Define inactivity clearly: Base your criteria on meaningful actions like clicks, conversions, or website visits.
Implement re-engagement campaigns: Before removal, send a series of emails with compelling offers and a clear call to action to reconfirm interest. Get tips on re-engaging inactive subscribers.
Sunsetting policy: Establish a clear timeline for when inactive subscribers will be removed from your active sending list after re-engagement efforts fail. This impacts your open rates.
Transitioning inactive subscribers
The transition period between defining inactivity and making the decision to sunset subscribers is critical. It involves careful monitoring and strategic actions to minimize negative impact on your sender reputation. Consider implementing a staged approach to inactive subscriber management.
For subscribers who consistently show proxy opens but no clicks, you might try a final, desperate attempt to re-engage them with a unique offer or a survey asking about their preferences. If this last-ditch effort yields no true engagement, it's time to move them off your active sending list. This reduces the number of emails sent to unengaged users, preserving your domain's health. You can learn how to manage deliverability when re-engaging.
For those you sunset, consider moving them to a 'suppression list' rather than deleting them entirely. This allows you to track them and prevent accidental resubscriptions. It also provides a record for compliance purposes, especially if regulations like GDPR apply to your audience. This process helps ensure best practices.
It's important to educate your team and stakeholders about the nuances of proxy opens and the importance of active list hygiene. Focusing on a smaller, truly engaged audience will yield better results in the long run than chasing inflated vanity metrics. This is how you can target inactive users without harming your domain reputation.
Views from the trenches
Best practices
**Prioritize clicks over opens:** Define inactivity based on actual clicks, conversions, or website activity rather than just opens.
**Implement multi-stage re-engagement:** Create a series of emails with escalating offers and clear calls to action to prompt real interaction.
**Use multiple channels:** Reach out to inactive subscribers through other channels like social media or retargeting ads.
**Clearly define sunsetting thresholds:** Establish a specific timeframe (e.g., 6-12 months of no engagement) after which subscribers are removed from active sending lists.
**Educate stakeholders:** Explain how proxy opens impact metrics and why list hygiene is crucial for deliverability, not just list size.
Common pitfalls
**Over-relying on open rates:** Assuming all opens indicate human engagement leads to inflated metrics and poor list quality.
**Ignoring proxy opens:** Failing to identify and segment proxy opens can mask true inactivity and harm sender reputation.
**Holding onto inactive subscribers too long:** Prolonged sending to unengaged users increases bounce rates, spam complaints, and risks hitting spam traps.
**Lack of clear re-engagement strategy:** Sending generic 'we miss you' emails without a strong incentive or clear call to action.
**Not using suppression lists:** Deleting inactive contacts instead of suppressing them can lead to accidental re-additions or loss of valuable data for analysis.
Expert tips
Consider embedding an invisible link within emails for advanced tracking of non-MPP clicks. This can help distinguish genuine interaction.
For transactional emails, focus on delivery and click-throughs to key actions rather than opens.
Regularly review your segments and adjust your inactivity definitions as email client behaviors evolve.
Leverage email authentication protocols like DMARC to build stronger sender trust and improve deliverability for engaged users.
Remember that not all subscribers who don't click are completely disengaged; some may prefer consuming content directly from the email body.
Expert view
Expert from Email Geeks says: Many recipients do not load images, leading to unrecorded "opens." Some users read emails and visit websites via other means without clicking through the email itself. A good strategy is to send re-engagement emails asking subscribers to click if they wish to continue receiving communications. Utilize sophisticated detection methods to identify those without genuine interaction before deciding on subscription status.
2024-05-20 - Email Geeks
Marketer view
Marketer from Email Geeks says: I am actively working to remove pre-fetch openers from our lists, as I believe they are negatively impacting our sender reputation, whereas previously they seemed benign. I've observed behavior, particularly from Gmail, suggesting a crackdown on these "vanity openers" that inflate open rates without true engagement.
2024-05-20 - Email Geeks
Prioritizing genuine engagement
The evolving landscape of email engagement, particularly with the rise of proxy opens, demands a more sophisticated approach to managing inactive subscribers. Simply tracking opens is no longer sufficient to gauge true engagement or maintain optimal deliverability.
By shifting focus to actionable engagement metrics like clicks and conversions, implementing smart segmentation, and executing thoughtful re-engagement and sunsetting strategies, you can ensure your email program remains healthy, efficient, and impactful. A clean, engaged list is your most valuable asset in email marketing, leading to better deliverability and higher returns on your efforts.
