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Unveiling the Secrets of Email Deliverability: Recent Research Findings
Inna Sabada
by Inna Sabada
Unveiling the Secrets of Email Deliverability: Recent Research Findings

Demystifying Email Deliverability: Uncovering the Latest Research Findings


Email remains a primary mode of communication, especially in the business world. However, the effectiveness of this communication tool hinges on one crucial factor: email deliverability. This term refers to the ability of an email to reach the intended recipient's inbox without being flagged as spam or bouncing back. With recent research shedding new light on the factors influencing email deliverability, it's time to delve into these findings and understand their implications. 


Historically, email deliverability has been a complex issue, with numerous factors at play. Previous studies have highlighted the role of sender reputation, email content, and recipient engagement in determining whether an email lands in the inbox or the spam folder. However, as email algorithms become more sophisticated, it's essential to stay updated with the latest research in this field.


New Research Findings


email deliverability statistic


The recent research on email deliverability has provided a more nuanced understanding of the key factors influencing it. 


Let's break down these findings:


1. Sender Reputation


Sender reputation is a score assigned to an email sender based on their email sending habits. It's measured by considering various factors like spam complaints, email volume, and bounce rates. The recent research found that a sender with a high reputation score is less likely to have their emails land in the spam folder. 


For instance, senders with a reputation score above 90 had a deliverability rate of 92%, while those with a score below 50 had a deliverability rate of just 45%.


2. Email Content


email statistic


The content of an email, including the subject line, body, and use of images, also plays a significant role in deliverability. The research found that emails with personalized subject lines had a 26% higher chance of being delivered successfully. 


Moreover, emails with a text-to-image ratio of 60:40 had a deliverability rate of 87%, highlighting the importance of balancing text and visuals.


3. Recipient Engagement


Recipient engagement refers to how recipients interact with the emails they receive. It's measured by open rates, click-through rates, and response rates. The research found a strong correlation between high recipient engagement and improved email deliverability. 


Emails from senders with high engagement rates (above 20%) had a deliverability rate of 89%, compared to just 65% for those with low engagement rates (below 10%).



4. The Changing Landscape of Open Rates: The Impact of Automatic Openings and Responses


Open rates, the percentage of recipients who open an email from the total number of emails sent, serve as a critical metric in understanding email deliverability. They provide valuable insight into how well your emails are received and engaged with by your audience. 


The study found a strong correlation between high open rates and improved email deliverability. Emails from senders with high open rates (above 20%) had a deliverability rate of 90%, compared to just 60% for those with low open rates (below 10%). This suggests that email providers consider open rates as a key indicator of the sender's relevance and value to the recipient.


Moreover, the research also highlighted the role of subject lines in boosting open rates. Emails with personalized subject lines had an open rate of 26% higher than those with generic subject lines. This underscores the importance of personalization in capturing the recipient's attention and improving overall email deliverability.


However, recent developments have cast a shadow of doubt over the reliability of open rates as a standalone indicator. The advent of automatic email openings and responses has introduced a new layer of complexity to the interpretation of open rates.


Automatic email openings occur when email clients automatically load images in an email, including the invisible pixel commonly used to track opens. This can inflate open rates, as the email is marked as 'opened' even if the recipient has not actually read the email. Similarly, automatic responses, such as out-of-office replies, can also skew open rates and other engagement metrics.


Recent research has highlighted the extent of this issue. The study found that automatic openings could inflate open rates by up to 50%. This means that an email campaign with an apparent open rate of 30% might actually have a true open rate of only 20%. 


These findings have significant implications for how businesses and individuals interpret and use open rates. While open rates can still provide valuable insights, they should not be relied upon as the sole indicator of email engagement or deliverability. Instead, it's important to consider a range of metrics, including click-through rates, response rates, and conversion rates.


5. Spam Folder: The Email Black Hole


spam folder


The spam folder, often referred to as the 'email black hole,' is the place where unwanted emails end up. It's a necessary evil, designed to protect users from potentially harmful or irrelevant content. However, for businesses and individuals sending legitimate emails, landing in the spam folder can significantly hinder communication efforts. 


Recent research has shed light on the factors that increase the likelihood of an email being classified as spam. Understanding these factors can help in devising strategies to avoid the dreaded spam folder and improve overall email deliverability.


1. Sender Reputation. As discussed earlier, sender reputation plays a crucial role in email deliverability. The research found that senders with a low reputation score are more likely to have their emails land in the spam folder. For instance, senders with a reputation score below 50 had a 55% chance of their emails being marked as spam.


2. Email Content. The content of an email, including the subject line, body, and use of images, can trigger spam filters. Emails with excessive use of capital letters, exclamation marks, or spam trigger words in the subject line were found to have a higher likelihood of ending up in the spam folder. Moreover, emails with a low text-to-image ratio were more likely to be classified as spam.


3. Recipient Engagement. Low recipient engagement can also lead to emails being marked as spam. If recipients frequently ignore your emails or mark them as spam, email providers may start automatically directing your emails to the spam folder.


4. Email List Quality. The quality of your email list also impacts whether your emails land in the inbox or the spam folder. The research found that email lists with a high number of inactive or invalid email addresses led to a higher spam rate.


The implications of these findings are clear. To avoid the spam folder and improve email deliverability, it's essential to maintain a good sender reputation, craft balanced and engaging email content, foster high recipient engagement, and ensure the quality of your email list.


6. The Role of Email Warm-Up Services in Improving Deliverability


email warm up


In the quest to improve email deliverability, one strategy that has gained significant traction is the use of email warm-up services. These services help enhance sender reputation by gradually increasing email sending volume, thereby reducing the likelihood of being flagged as spam.


Email warm-up services work by automatically sending emails from your account to other accounts within the service's network. These emails are then opened, marked as important, and replied to, mimicking genuine email activity. This process helps to establish a positive sending reputation with email providers, leading to improved email deliverability.


Among the various email warm-up services available, stands out for its effectiveness and user-friendly approach. offers a comprehensive warm-up plan that is tailored to the specific needs of your email account. It gradually increases the number of emails sent from your account, carefully monitors responses, and adjusts the warm-up process as needed.


Recent research supports the effectiveness of using email warm-up services like The study found that email accounts using saw a significant improvement in their email deliverability. Specifically, these accounts experienced a 25% increase in their emails reaching the inbox compared to accounts not using an email warm-up service.


The implications of these findings are profound for businesses and individuals alike. To improve email deliverability, it's crucial to maintain a good sender reputation, craft engaging and balanced email content, and foster high recipient engagement. This might involve practices like monitoring email metrics, personalizing email content, and segmenting email lists based on recipient behavior.


Want to know what your email deliverability rate is, take our free Email Deliverability Test.


🔹 Conclusion


In conclusion, email deliverability is a multifaceted issue, with sender reputation, email content, and recipient engagement playing pivotal roles. By understanding these factors and implementing the right strategies, businesses and individuals can significantly enhance their email deliverability. Future research might explore other potential influences on email deliverability, such as the impact of email frequency or the optimal time of day for sending emails.



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