Why are my email open rates low and how can I improve deliverability?
Michael Ko
Co-founder & CEO, Suped
Published 3 May 2025
Updated 16 Aug 2025
8 min read
It is incredibly frustrating when you send out important emails, only to find your open rates are alarmingly low. Often, the immediate thought is that these messages are ending up in the spam or junk folder, completely bypassing the intended recipient's inbox. I've seen this scenario play out countless times, and the impact on communication, engagement, and even revenue can be significant.
Low open rates are a strong indicator of underlying deliverability issues. It means that your emails, for one reason or another, aren't even getting the chance to be seen. This could stem from a variety of factors, ranging from technical misconfigurations to content problems or even the recipient's lack of interest.
In this guide, I'll explore the common culprits behind low email open rates and provide actionable steps you can take to diagnose and significantly improve your email deliverability, ensuring your messages reach the inbox where they belong.
Why emails don't reach the inbox
When your email open rates plummet, the first place to look is your email deliverability. Deliverability isn't just about whether an email is sent or not; it's about whether it successfully lands in the recipient's primary inbox, rather than getting diverted to the spam folder, promotions tab, or being blocked entirely. This directly impacts whether your audience even sees your subject line. If emails consistently miss the inbox, naturally, your open rates will suffer.
A key factor here is your sender reputation. Internet Service Providers (ISPs) like Google and Microsoft continuously evaluate your sending practices. If they detect suspicious activity, low engagement, or high spam complaints, your sender reputation takes a hit. A poor reputation tells ISPs that your emails might be unwanted, leading them to route your messages away from the main inbox. This cycle can be tough to break, so identifying the root cause is crucial.
It is also important to differentiate between types of emails. Transactional emails, like order confirmations or password resets, generally have higher deliverability expectations because they are anticipated. Marketing or bulk emails, however, are subject to more stringent filtering. If both types of your emails are seeing low open rates, it points to a broader deliverability challenge that needs a comprehensive approach, as explored in articles like what actually matters now in email marketing. Understanding why your emails are going to spam is the first step.
Ensure your technical setup is robust
A fundamental aspect of email deliverability lies in your email authentication protocols. SPF, DKIM, and DMARC are crucial for proving that your emails are legitimate and haven't been tampered with. Without these properly configured, ISPs are more likely to flag your emails as suspicious or even outright reject them, leading to a significant drop in open rates because the emails never even reach the recipient.
SPF (Sender Policy Framework) lets receiving servers verify that an email claiming to come from your domain is sent by an IP address authorized by your domain's administrators. DKIM (DomainKeys Identified Mail) adds a digital signature to your emails, allowing recipients to verify that the email was not altered in transit. DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, giving you control over what happens to emails that fail authentication. For a more detailed look, check out this simple guide to DMARC, SPF, and DKIM.
Misconfigurations in these records are a common reason for poor deliverability. I often see cases where a missing SPF record, an incorrect DKIM signature, or a DMARC policy that is too strict for current sending practices leads to emails being rejected. It is essential to ensure these DNS records are accurately set up for all services sending email on behalf of your domain. If you are starting with DMARC, a p=none policy is a safe starting point to gather data without impacting delivery.
This DMARC record sets a policy to quarantine emails that fail authentication, sends forensic reports to abuse@example.com, and aggregate reports to dmarc_reports@example.com. It also specifies relaxed alignment for DKIM and SPF.
Optimise content and foster engagement
Even with perfect technical setup, low open rates can persist if your content isn't compelling or your audience isn't engaged. ISPs increasingly consider engagement metrics when determining inbox placement. If subscribers consistently ignore your emails, mark them as spam, or delete them without opening, this signals to ISPs that your content might not be relevant or wanted, which can lead to future messages being filtered to spam.
Crafting engaging subject lines is paramount; it's the first impression and often the deciding factor for an open. Personalization goes beyond just using a recipient's first name, it involves segmenting your audience and sending targeted content that resonates with their specific interests and needs. Avoid spam trigger words in your subject lines and email body that commonly cause filters to flag messages. Focus on providing value, whether it's through helpful information, exclusive offers, or entertaining content, as this helps to focus on engagement and boost your sender reputation.
Furthermore, maintaining a clean and active email list is critical. Sending emails to inactive or invalid addresses inflates your bounce rates and lowers your overall engagement, which negatively impacts deliverability. Regularly cleaning your list by removing unengaged subscribers and invalid addresses can significantly boost your open rates and inbox placement. Consider implementing re-engagement campaigns for inactive subscribers before removing them entirely. Increasing your email click through rate often correlates with better open rates too.
Causes of low engagement
Irrelevant content: Emails that do not match subscriber expectations or interests.
Poor subject lines: Generic, misleading, or spammy subject lines that fail to entice opens.
Infrequent list cleaning: Sending to unengaged or inactive subscribers, which drags down overall open rates.
Strategies for higher engagement
Audience segmentation: Tailor content to specific segments of your list.
A/B test subject lines: Experiment with different subject lines to find what resonates best.
Regular list hygiene: Remove inactive and invalid addresses to improve engagement metrics.
Proactive monitoring and list hygiene
Even after implementing best practices, continuous monitoring is non-negotiable for maintaining good email deliverability and open rates. Deliverability is not a set-it-and-forget-it task; it requires ongoing attention. Key metrics to watch include bounce rates (hard and soft), spam complaint rates, and engagement over time (opens, clicks, replies).
A sudden drop in open rates often indicates that your domain or IP address may have been added to an email blocklist (or blacklist). These lists are maintained by various organizations to identify and block sending IPs or domains associated with spam. If you find your domain on a blocklist, it can severely impact your ability to reach the inbox. Understanding how email blacklists actually work is essential for quick remediation. The good news is that most blocklists have a delisting process, but it requires addressing the underlying cause of the listing, which often relates to poor sending practices.
Regularly cleaning your email list is perhaps the most impactful ongoing task. Inactive subscribers, or those who haven't opened or clicked your emails in a long time, hurt your sender reputation and inflate your subscriber count without contributing to engagement. Removing them helps you send to a more engaged audience, which signals positively to ISPs. For comprehensive insights, learn how to improve email deliverability.
Issue
Impact on deliverability
Monitoring method
High bounce rate
Signals a poor list quality or invalid addresses, harming sender reputation.
Check email service provider reports, hard/soft bounce categories.
Spam complaints
Directly indicates unwanted emails, leading to blocklisting or inbox filtering.
Review feedback loops (FBLs) with ISPs, monitor ESP reports.
Blocklist status
Prevents emails from reaching major ISPs, causing severe deliverability issues.
Regularly audit your email authentication (SPF, DKIM, DMARC) to ensure records are correct.
Segment your audience to send highly relevant content, improving engagement metrics.
Implement a consistent list cleaning process to remove unengaged or invalid subscribers.
Common pitfalls
Ignoring low open rates across specific providers like Microsoft or Google, indicating ISP-specific blocks.
Failing to monitor bounce rates and spam complaints, which degrade sender reputation over time.
Sending emails to purchased or old lists, leading to high bounces and spam trap hits.
Expert tips
Warm up new sending IPs or domains gradually to build a positive reputation with ISPs.
Personalize subject lines and content based on recipient behavior and preferences.
Regularly check major blocklists and promptly request delisting if your domain or IP is listed.
Marketer view
A marketer from Email Geeks says that if open rates are dropping evenly across all providers, it could be due to recipients not finding the subject line or brand interesting, rather than a specific deliverability problem.
2022-07-21 - Email Geeks
Expert view
An expert from Email Geeks says that focusing on engagement is crucial for boosting sender reputation and improving deliverability.
2022-06-25 - Email Geeks
Taking control of your email deliverability
Low email open rates are a clear signal that your messages are not consistently reaching the inbox. Addressing this challenge requires a multi-faceted approach, combining robust technical configurations, engaging content, and diligent list management.
By ensuring your authentication protocols are correctly set up, regularly cleaning your email list, and consistently delivering valuable and relevant content, you can significantly improve your sender reputation and, by extension, your email deliverability. This proactive strategy will help ensure your emails land where they can be seen and acted upon, leading to better engagement and ultimately, better results for your email campaigns.
Google and 
Microsoft continuously evaluate your sending practices. If they detect suspicious activity, low engagement, or high spam complaints, your sender reputation takes a hit. A poor reputation tells ISPs that your emails might be unwanted, leading them to route your messages away from the main inbox. This cycle can be tough to break, so identifying the root cause is crucial.
