Are opens still a reliable metric for engagement in re-warming sender reputation?

Yes, including opens can be beneficial. While clicks are a stronger indicator of engagement, opens (even if influenced by Apple's Mail Privacy Protection) still signal to ISPs that the email address is valid and that the email is not immediately considered spam. This broader inclusion can help generate sufficient volume for effective re-warming, especially if your list of clickers is small.

Why are engagement cohorts important for re-warming?

The primary goal of re-warming is to demonstrate positive sending behavior to mailbox providers. Engagement cohorts, whether based on opens, clicks, or both, help you target the most responsive users. This generates positive signals that improve your sender reputation and increase the likelihood of future emails reaching the inbox instead of the spam folder .

How do I build effective engagement cohorts for re-warming?

Start by identifying your most recent and active subscribers, segmenting them by their last open or click. Begin sending to these top-tier engaged users with highly relevant content. As your reputation improves, gradually expand your cohorts to include users with slightly older engagement. Continuously monitor your bounce rates, spam complaints, and inbox placement.

When should I consider excluding opens from my engagement cohorts?

While you might initially include opens, if your deliverability doesn't improve or you notice increased spam complaints, consider narrowing your focus to only clicks. This ensures you are sending to the most explicitly engaged users. Also, review your email content for relevance and engagement-driving elements.

Beyond opens and clicks, what other factors should I consider when re-warming?

Regularly clean your email list by removing hard bounces and subscribers who have not engaged in a significant period (e.g., 6-12 months). This helps prevent hitting spam traps and ensures you're sending to a healthy, responsive audience, which is fundamental to maintaining a strong sender reputation.

Should I include opens when building engagement cohorts for re-warming sender reputation? - Sender reputation - Email deliverability - Knowledge base

When re-warming a sender reputation, building effective engagement cohorts is critical. The quality of these cohorts directly influences how quickly and successfully your domain or IP address recovers. A common question arises: should email opens be included when defining these engagement cohorts, or should the focus strictly be on clicks?

This decision impacts the integrity of your warming strategy. Mailbox providers (ISPs) like

Google and

Outlook constantly evaluate your sending behavior, with user engagement being a primary factor. Understanding how different engagement metrics are perceived is key to navigating this process successfully.

In this discussion, I'll explore the role of opens in re-warming efforts, the nuances of engagement signals, and provide guidance on how to build robust cohorts that genuinely support your sender reputation.

The importance of engagement in sender reputation re-warming

Sender reputation is the cornerstone of email deliverability. It's a score assigned to your sending domain and IP address by mailbox providers, indicating how trustworthy you are as a sender. This score is influenced by numerous factors, with user engagement being paramount. High engagement signals to ISPs that your emails are valued and relevant, leading to better inbox placement.

When your sender reputation has declined, re-warming is a strategic process to rebuild trust. This involves gradually increasing sending volume to highly engaged segments of your list. The goal is to demonstrate consistent positive engagement, such as opens and clicks, while avoiding negative signals like spam complaints or bounces. This careful approach helps avoid blocklists (or blacklists) and improve your domain reputation.

Positive engagement is truly the heartbeat of your warming strategy. Without it, even the most well-intentioned campaigns can struggle to improve sender reputation, as noted on Quora's discussion on email engagement. It's about showing mailbox providers that recipients genuinely want and interact with your emails.

The nuances of opens and clicks

The landscape of email opens has changed significantly, particularly with Apple's Mail Privacy Protection (MPP). MPP pre-fetches images, making many reported opens unreliable as a direct indicator of user engagement. This means an open might not represent a human interaction. However, this doesn't render opens entirely useless.

Mailbox providers still consider opens as a signal, even if the signal is indirect. The act of an ISP pre-fetching images often indicates that the email address is deemed legitimate and the email itself is not immediately flagged as spam. Therefore, while not a perfect measure of engagement, opens still contribute to the overall impression your sending behavior makes on an ISP.

Clicks, on the other hand, are a much stronger and more reliable indicator of active user engagement. A click unequivocally demonstrates that a recipient was interested enough to interact with your email content. When rebuilding your reputation, prioritizing clicks provides a clear, undeniable positive signal to mailbox providers. However, a strategy that only uses clicks might significantly reduce the available pool of engaged subscribers, especially for smaller lists.

Metric	Reliability for Engagement	ISP Perception
Opens	Lower due to MPP, but still indicative of address validity and potential pre-fetching by ISPs.	A soft positive signal; can suggest recipient interest or ISP acceptance.
Clicks	High reliability; directly indicates user interaction and interest.	A strong positive signal; heavily weighted in sender reputation algorithms.

Building effective engagement cohorts

When re-warming your sender reputation, creating engagement cohorts means segmenting your audience based on their recent interactions. The goal is to start sending to the most responsive users first, gradually expanding to broader segments as your reputation improves. This is a common practice, as highlighted by Leanplum's IP warm-up guidelines, which suggest starting with users who opened emails in the last 0-3 months.

Including opens in your engagement cohorts, alongside clicks, can broaden your pool of engaged contacts. While clicks are definitive, relying solely on them might mean you're excluding a portion of your audience that is still actively receiving and opening your emails, even if they aren't clicking. This is particularly relevant if you are facing challenges like rebuilding Gmail sender reputation with limited subscribers.

Strategy: opens and clicks

Many email service providers (ESPs), including Klaviyo, recommend including opens when segmenting for re-engagement or re-warming. This approach is based on the premise that even a pre-fetched open indicates some level of ISP acceptance and a valid email address, contributing positively to your IP warming efforts.

Benefits: Larger pool of engaged contacts, faster initial warm-up, leverages ISP pre-fetching signals.
Considerations: Less precise measure of explicit engagement, requires careful monitoring for potential machine opens.

Strategy: clicks only

Focusing solely on clicks provides the purest form of explicit engagement. This method ensures that every recipient in your re-warming cohort has taken a direct action, signaling strong interest in your content. This is a conservative yet highly effective approach for reputation repair.

Benefits: Highest quality engagement signal, minimizes risk of sending to less engaged users or spam traps.
Considerations: Smaller cohort size, slower ramp-up if clicks are low, potentially excludes valid, interested recipients.

Practical application and monitoring

My recommendation leans towards including opens, especially when dealing with a diminished sender reputation or a smaller list where every positive signal counts. The key is to be strategic about it. Start with your most recently engaged subscribers, prioritizing those with clicks, but don't shy away from including those with recent opens if your click volume is insufficient.

As your reputation improves, you can gradually expand your cohorts to include users with older engagement. However, continuously monitor your deliverability metrics. Pay close attention to bounces, spam complaints, and overall inbox placement. If you see negative trends, it may indicate that some of your unengaged users are causing issues.

Best practice for re-warming

To effectively re-warm your sender reputation, start by segmenting your most active users based on recent opens and clicks. Gradually increase your sending volume to these engaged segments over time. Monitor your deliverability rates and adjust your sending plan based on performance. Always clean your list by removing hard bounces and unengaged subscribers to maintain a healthy sending environment. Consider how to exclude unengaged email subscribers for improved deliverability.

Views from the trenches

Best practices

Start re-warming with your most engaged subscribers, including recent clickers and openers, especially when repairing reputation or dealing with small lists.

Segment your list based on engagement levels, moving from highly engaged to less engaged over time, using both opens and clicks.

Continuously monitor all key deliverability metrics, including open rates, click-through rates, bounce rates, and spam complaint rates.

Common pitfalls

Relying solely on clicks can severely limit your re-warming cohort size, slowing down the reputation repair process.

Failing to filter out bot clicks or inflated opens can skew your engagement metrics and hinder accurate assessment of your list's health.

Ignoring negative signals like high bounce rates or spam complaints during re-warming, which can further damage your sender reputation.

Expert tips

Consider a combined strategy: prioritize clicks for the initial, most critical phases of re-warming, then gradually incorporate recent opens as your confidence grows and data supports it.

For very small or severely damaged lists, opens might be a necessary inclusion to achieve sufficient volume for meaningful warming.

Always maintain a clean list by regularly removing unengaged subscribers and bounced email addresses, as this fundamental practice supports all deliverability efforts.

Marketer view

Marketer from Email Geeks says: You should generally use both clicks (while excluding bot clicks) and opens when building engagement cohorts.

2024-05-21 - Email Geeks

Marketer view

Marketer from Email Geeks says: While opens might be overstated due to privacy changes, including them is unlikely to impede your reputation repair efforts significantly.

2024-05-21 - Email Geeks

Finding the right balance for reputation re-warming

Ultimately, the decision to include opens when building engagement cohorts for re-warming sender reputation is nuanced. While clicks offer a stronger, more explicit signal of engagement, opens still play a role in how mailbox providers perceive your sending activity. Especially when rebuilding a damaged reputation or working with smaller lists, including opens can provide a broader base of engaged users to help accelerate the warming process.

The most effective approach combines both metrics, starting with your most recently active subscribers (those who have clicked or opened) and carefully expanding your audience over time. Consistent monitoring of your deliverability metrics and adapting your strategy based on real-time performance are crucial for success.

By thoughtfully constructing your engagement cohorts and paying close attention to your sending patterns, you can effectively rebuild and maintain a strong sender reputation, ensuring your emails consistently reach the inbox.