What are the best alternative metrics to email open rates for measuring engagement?
Michael Ko
Co-founder & CEO, Suped
Published 5 Jul 2025
Updated 16 Aug 2025
6 min read
For years, email open rates were a cornerstone of email marketing analytics, serving as a seemingly straightforward indicator of engagement. They offered a quick glance at how many recipients bothered to even look at your email. However, the landscape has changed significantly, particularly with privacy-enhancing features like Apple Mail Privacy Protection (MPP). These changes have rendered open rates increasingly unreliable and, in some cases, misleading.
The automatic loading of images (which is how opens are typically tracked) means that an email may be counted as opened even if the recipient never actually viewed it. This shift necessitates a re-evaluation of how we measure email engagement, urging marketers to look beyond the traditional open rate and embrace more accurate, action-oriented metrics.
Beyond the open: focusing on direct interaction
While open rates may offer some directional insight, they are no longer the definitive measure of whether your audience is connecting with your content. The focus has rightly shifted to direct interactions within the email itself. These actions provide a clearer picture of recipient interest and the effectiveness of your message.
Click-Through Rate (CTR) measures the percentage of recipients who clicked on one or more links in your email. This metric is a strong indicator of content relevance and the effectiveness of your call-to-action. If people are clicking, it means your message resonated enough to prompt further exploration.
Click-to-Open Rate (CTOR) takes CTR a step further by calculating the percentage of unique clicks relative to unique opens. This provides a more refined view of engagement among those who actually opened your email. A high CTOR indicates that your email content is compelling and effectively drives interaction once opened, showcasing the quality of your message design and targeting.
While the raw open rate might be inflated by bot clicks and platform limitations, focusing on CTR and CTOR helps you assess genuine subscriber interest and the effectiveness of your content in prompting action. These metrics directly reflect active engagement, which is crucial for building a healthy sender reputation.
Why CTR and CTOR matter
Unlike open rates, Microsoft and other ISPs highly value actual clicks. They signal genuine interest, indicating that your subscribers find your content relevant. This positive interaction directly influences your sender reputation, making it more likely your emails will land in the inbox rather than the spam folder. Prioritizing these metrics is essential for long-term deliverability success.
Measuring active subscriber behavior
Beyond clicks within the email, true engagement extends to actions taken after a recipient interacts with your message. These post-click behaviors offer invaluable insights into how your email campaigns contribute to broader business goals.
Conversion rate is arguably the most important metric for many email marketers. It measures the percentage of recipients who complete a desired action, such as making a purchase, signing up for a webinar, downloading content, or filling out a form, after clicking a link in your email. This directly ties your email efforts to tangible business outcomes.
Reply rate is another powerful indicator, especially for sales or customer service emails. A reply signifies active participation and a deeper level of engagement than a mere click. It often precedes a direct conversation, indicating a strong interest in your offerings or content.
Website visits and time on page after an email click reveal how captivating your linked content is. Integrating UTM parameters into your email links allows you to track specific campaigns within your web analytics, providing a comprehensive view of user journey and content consumption. A user spending significant time on your site after an email click indicates high engagement.
Read time and skim time metrics are emerging as valuable alternatives, particularly with advanced email analytics platforms. They estimate how long a recipient spent actively viewing your email, differentiating between a quick glance (skim) and thorough consumption (read). While not universally available, these metrics can offer a nuanced understanding of content resonance beyond a simple click. Some ESPs and tools can provide this by tracking scroll depth or cursor activity, even without a click.
Less insightful engagement metrics
Open rate: Inflated by Mail Privacy Protection, bots, and pre-fetching, leading to inaccurate data on actual views. It no longer reliably indicates active interest.
Image pixel tracking: Relies on images loading, which can be blocked by recipients or pre-loaded by mail clients, skewing open rate data.
More insightful engagement metrics
Click-Through Rate (CTR): Measures direct user action, indicating content relevance and call-to-action effectiveness.
Conversion rate: Tracks completed actions (e.g., purchases, sign-ups) that directly impact business goals.
Website engagement: Analyzing post-click behavior like time on site, pages visited, and bounce rate provides deeper insights.
Read and skim time: Indicates how long recipients interact with the email, offering a nuanced view of content consumption.
Understanding negative signals
While positive engagement metrics are crucial, understanding and mitigating negative signals are equally important for maintaining a strong sender reputation and ensuring your emails reach the inbox. These metrics highlight areas where your email strategy might be falling short.
Bounce rate measures the percentage of emails that couldn't be delivered. High bounce rates signal issues with your mailing list quality or potential blocklist (or blacklist) problems. Soft bounces are temporary issues (e.g., full inbox), while hard bounces are permanent (e.g., invalid address). Regularly cleaning your list to remove hard bounces is vital.
Unsubscribe rates indicate how many recipients opted out of your emails. While a certain level is normal, a spike suggests content misalignment, excessive frequency, or a general lack of perceived value. Similarly, spam complaint rates are a critical negative signal. When recipients mark your email as spam, it severely damages your sender reputation and increases the likelihood of future emails landing in the spam folder or your domain ending up on a blocklist (or blacklist). Maintaining healthy engagement thresholds for these negative metrics is paramount.
Common SMTP bounce codesplaintext
550 5.1.1 <user@example.com>: Recipient address rejected: User unknown in virtual alias table
554 5.7.1 Service unavailable; Client host [X.X.X.X] blocked using zen.spamhaus.org; See: http://www.spamhaus.org/query/bl?ip=X.X.X.X
450 4.2.2 The recipient's mailbox is full and cannot accept messages at this time.
Metric
What it measures
Importance
Click-Through Rate (CTR)
Percentage of recipients who clicked a link in the email.
Direct indicator of content relevance and call-to-action effectiveness.
Conversion Rate
Percentage of recipients who completed a desired action post-click.
Measures the direct business impact and ROI of email campaigns.
Unsubscribe Rate
Percentage of recipients who opted out of receiving future emails.
Indicates subscriber disinterest, content fatigue, or frequency issues.
Spam Complaint Rate
Percentage of recipients who marked the email as spam.
Critical negative signal affecting sender reputation and deliverability.
Read/Skim Time
Estimated duration a recipient spent viewing the email.
Provides a nuanced understanding of content consumption and interest.
Embracing a holistic view of engagement
Measuring email engagement effectively in today's environment means moving past a singular reliance on open rates. A holistic approach that considers a combination of metrics provides a more accurate and actionable understanding of your audience's interaction with your emails. This comprehensive view not only helps you refine your content strategy but also plays a vital role in maintaining a healthy sender reputation and optimal inbox placement.
By shifting your focus to clicks, conversions, and subscriber behavior, you can gain deeper insights into what truly resonates with your audience and make data-driven decisions that lead to stronger email performance. Prioritizing these action-oriented engagement metrics is essential for long-term email marketing success and deliverability.
Views from the trenches
Best practices
Always prioritize click-through rate (CTR) and conversion rate over open rates to gauge true engagement and campaign effectiveness.
Segment your audience based on past engagement to tailor content, improving relevance and reducing unsubscribes.
Regularly clean your email list to remove inactive subscribers and hard bounces, protecting your sender reputation.
Test different calls-to-action and email designs to optimize for clicks and conversions.
Implement a feedback loop for spam complaints to quickly identify and address issues, maintaining good deliverability.
Common pitfalls
Over-relying on open rates as the primary success metric, leading to misleading insights and poor optimization decisions.
Ignoring negative engagement metrics like bounce rates and unsubscribe rates, which can silently erode sender reputation.
Sending emails too frequently or with irrelevant content, causing subscriber fatigue and increased spam complaints.
Failing to segment your audience, resulting in generic emails that don't resonate with specific subscriber interests.
Not integrating email metrics with web analytics, missing the full picture of post-click user behavior and conversions.
Expert tips
Consider tracking 'read time' and 'skim time' if your email service provider offers these advanced analytics, as they offer deeper insights into content consumption patterns.
Focus on the 'Click-to-Open Rate' (CTOR) to understand how engaging your content is among those who actually open your emails, providing a more refined view than simple CTR.
Monitor your domain reputation through Google Postmaster Tools and other resources, as positive engagement metrics directly influence how ISPs view your sending practices.
For transactional emails or important updates, track reply rates, as a direct reply indicates high recipient interest and can open a direct line of communication.
Utilize UTM parameters in all your email links to gain granular insights into traffic sources and user behavior on your website from specific campaigns.
Marketer view
Marketer from Email Geeks says that while open rates still offer some context, click rate has become the main metric to focus on for engagement, and they also suggest monitoring web and social media interactions.
2022-05-13 - Email Geeks
Marketer view
Marketer from Email Geeks says they are increasingly looking at interactions like read and skim rates in addition to clicks to understand engagement.
