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What Affects Email Deliverability? Unveiling the Top Factors

For your emails to make an impact, they must first reach the recipient’s inbox. Many factors, from authentication protocols to content structure, play a vital role in whether an email lands in the inbox or gets banished to the spam folder. 

We will provide you with an in-depth understanding of what affects email deliverability to help you better reach your audience’s inbox. Let’s dissect the factors that can make or break your email campaign’s success.

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What Determines Email Deliverability?

Internet Service Providers (ISPs) and other entities have control over whether your emails reach their intended recipients. They play a crucial role in determining email deliverability. 

Email deliverability refers to the ability of an email to successfully reach its intended recipient’s inbox without being blocked or marked as spam.

The ISP’s spam filters, algorithms, and reputation systems assess various factors to decide whether an email should be delivered to the inbox, marked as spam, or blocked entirely. These factors include sender reputation, email content, engagement rates, list hygiene, domain authentication, and compliance with regulations such as GDPR. To improve, it is essential to follow the best practices for email deliverability.

There are many factors that influence email deliverability. We delve into what exactly impacts how your emails land in the recipient’s inbox.

Subscriber Engagement

Engagement is an integral factor that influences email deliverability. The era where only negative feedback mattered has evolved, and now positive engagement plays a significant role in determining if your emails hit the inbox or the spam folder.

Positive engagement has become one of the most critical factors affecting deliverability. Mailbox providers regard actions such as email opens, clicks, replies, or moving an email from the spam folder to the inbox as positive engagement signals. These signals indicate that recipients are interested in and value the emails they are receiving. Managing inactive subscribers by reducing email frequency to less engaged subscribers and eventually suppressing subscribers who haven’t engaged in a long time is necessary. This helps in focusing on sending emails to those who are genuinely interested, which in turn, boosts the engagement rates.

Mobile optimization is also a factor in engagement. Since a significant portion of emails is accessed via mobile devices, ensuring your emails are mobile-friendly can positively affect engagement rates. This includes having a responsive design that adjusts to different screen sizes and ensuring that links and calls to action are easily clickable.

Include a easily viewed unsubscribe link on all your emails delivered. Of course, you wouldn’t want people to unsubscribe from your mailing list, but if they are not opening or engaging with your emails, you should easily provide the with the option to opt out.

Subscriber engagement and feedback are crucial elements in email deliverability. Sending content that resonates with and is valued by the recipients, optimizing for mobile devices, and actively managing your subscriber list for engagement can significantly improve your email deliverability rates. It’s important for senders to monitor email engagement metrics and adjust their strategies accordingly continuously.

Spam Feedback

Mailbox providers heavily weigh both negative and positive feedback. Negative feedback primarily comes in the form of spam complaints. A high rate of spam complaints can be detrimental to your sender reputation and thereby affect your email deliverability. Recipients might mark your emails as spam for various reasons, including not remembering to opt in, difficulty in unsubscribing, or merely no longer finding the content relevant or interesting. Keeping the spam complaint rate very low is imperative. For instance, if more than 0.1% of a brand’s subscribers report their emails as spam, they may experience blocking or their emails being marked as junk.

It’s important to note that spam email feedback loops play a pivotal role in subscriber engagement.

Eeedback loops enable senders to receive feedback directly from mailbox providers regarding how recipients interact with their emails. This allows senders to understand what kind of content engages their audience and what leads to spam complaints.

Note: Before you send any emails, review our email deliverability checklist to maximize your visibility in the inbox. 

Domain Authentication

Domain authentication is one of the cornerstones in ensuring that the emails you send are delivered successfully to the recipient’s inbox. It acts like a digital signature that confirms to mailbox providers that an email claiming to come from a specific domain is authorized by the owner of that domain.

Implementing SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) records as part of your domain authentication.

SPF is an email authentication technique which prevents spammers from sending messages on behalf of your domain. Specifically, SPF records verify that the sending IP address is authorized to send emails for your domain. This is essential because, without it, spammers could easily send emails that appear to be from your domain, potentially tarnishing your reputation and deliverability.

DKIM adds an encrypted signature to the header of all outgoing messages. This signature is specific to your domain, and only the email server with the corresponding private key can send emails on behalf of your domain. It guarantees that the content of your email has not been altered in transit. This is crucial as it assures the recipient’s email server that the email contents are intact and haven’t been tampered with, adding layer of trust.

DMARC is built on top of SPF and DKIM protocols, allowing the domain owner to indicate that SPF and DKIM protect their emails. It also tells the mailbox provider what to do if an email doesn’t pass SPF or DKIM authentication (such as to reject the message or send it to the spam folder). This adds a level of policy enforcement that is communicated to the receiving email server, thus ensuring that unauthenticated emails are handled according to the sender’s stated policy.

You build a positive sender reputation by authenticating your domain through SPF, DKIM, and DMARC. Mailbox providers are more confident that the emails they are receiving from your domain are genuine and not spam or phishing attempts. This trust is often rewarded with higher deliverability rates as mailbox providers are less likely to flag your emails as spam.

It’s not just the IP addresses that matter; mailbox providers also attach the sender’s reputation to the domains they use. Therefore, having properly authenticated domains is not a mere technical requirement but a significant contributor to the trustworthiness and credibility of your email communications.

List Hygiene

Maintaining an immaculate email list is essential for ensuring high deliverability rates. List hygiene, which means regularly cleaning your email list by removing inactive or invalid email addresses, affects deliverability. Sending emails to non-existent addresses or spam traps can harm your email deliverability.

Invalid or non-existent email addresses can lead to a high bounce rate. There are two categories of bounces – hard and soft. A hard bounce occurs when an email is sent to an address that doesn’t exist or is no longer in use. Soft bounces may occur due to temporary issues such as a full inbox. If more than 2% of a brand’s emails hard bounce in a month, it impacts their deliverability negatively.

Sending emails to spam traps is a red flag for mailbox providers. Spam traps are email addresses used solely to catch spammers, and mailbox providers can create them or can be old addresses that are no longer in use. Hitting even a few spam traps indicates poor list hygiene and can lead to serious email deliverability problems.

Email Volume and Sending Patterns

The volume of emails sent and the pattern in which they are sent play a crucial role in email deliverability. Mailbox providers are more vigilant towards brands that send large volumes of emails. Sending a high volume of emails, especially suddenly and unpredictably, can be a red flag for mailbox providers, as this behaviour is typical of spammers.

Predictable and relatively consistent sending patterns are more favourable. While this does not mean that the volume has to be the same every day, it is essential to avoid dramatic fluctuations. For example, it is common for brands to send more emails during certain seasons, like holidays or sale periods. Brands should gradually ramp up the volume over weeks heading into these high-frequency seasons. This gradual increase helps maintain a consistent sending pattern and avoid sudden spikes, which can harm deliverability.

A new dedicated IP address must warm up to build a positive reputation first. Here’s how to warm up an IP address for sending emails.

Small senders have an advantage as they often send their emails over shared IP addresses along with other small senders. This helps even out the email volume, making it appear more consistent to mailbox providers. However, large senders must be more cautious and strategic in their sending patterns.

It’s crucial to consider the nature of the content being sent. If the emails contain time-sensitive information or are part of a campaign, planning and scheduling the sending pattern in advance is essential. This helps maintain a consistent sending pattern and ensures the emails are delivered at the right time to maximize engagement.

Considering these factors, it becomes evident that a well-thought-out strategy for email volume and sending patterns is essential for maintaining good deliverability rates. By gradually increasing volume during high-frequency seasons, ensuring consistency, and carefully planning the timing of emails, brands can ensure that their emails are delivered and well-received by the subscribers.

Content of the Email

The content of the email, including its structure and the elements within, is a significant factor in email deliverability. It’s important to note that while in the past, the usage of certain words, punctuation, and text-to-image ratio were critical elements in email filtering, these aspects are now much less consequential. You still want to avoid overly spammy words in your emails, but now algorithms are better at understanding promotional content versus non-promotional.

Balancing promotional content with non-promotional elements affect email deliverability. The algorithms don’t simply count the number of promotional words; they evaluate the percentage of the promotional email. By extending the length of the email with non-promotional content, you can improve your deliverability.

Mailbox providers closely examine the code of the email. They look for potentially malicious elements, such as embedded tags or JavaScript, that can be used for malicious purposes. It’s important to avoid incorporating any code that could be construed as harmful.

In addition to scanning for potentially malicious code, mailbox providers also evaluate the cleanliness and structure of the code. Well-structured code with properly closed tags is considered a sign of a legitimate and professional email. This implies that the email sender has put thought into creating a clean and user-friendly layout, which is often indicative of a reputable brand.

Another critical aspect of email content is the URLs included within the email. Emphasizes that mailbox providers heavily scrutinize the URLs in an email. Including links to websites that have a poor reputation can negatively impact deliverability. This is because spammers often link to questionable or harmful websites, and by including such links, legitimate senders may inadvertently be lumped in with malicious actors.

The use of URL shorteners can be problematic. Spammers frequently use URL shorteners to mask the destinations of their links, which can lead mailbox providers to view shorteners with suspicion. Therefore, using full, clear URLs is advisable, especially when linking to reputable sites.

Pay attention to the relevance and value of the content to the recipients. Sending content that meets the needs and interests of the recipients can lead to higher engagement, which in turn positively impacts deliverability.

It is essential to ensure clean and non-malicious code, include reputable URLs, and provide valuable and relevant content to the recipients.

Sender Reputation

Sender reputation plays a crucial role in email deliverability. Mailbox providers calculate sender reputation based on a combination of the factors discussed earlier. It is not only associated with the IP addresses used by the sender but also the domains they use.

IP Reputation

The reputation of the IP address used to send emails is an important factor in sender reputation. Mailbox providers evaluate the sending patterns, engagement rates, and spam complaints associated with the IP address. A history of sending high-quality, engaging emails with low spam complaint rates can contribute to a positive IP reputation.

Dedicated IP addresses are solely used to send your emails, providing you with full control over your sender reputation. By sending emails from an address exclusively assigned to you, you can ensure that your email deliverability is not affected by the actions of other senders sharing the same IP address. This allows you to maintain a positive sender reputation and optimize the deliverability of your emails.

Domain Reputation

Alongside IP reputation, the reputation of the domain used by the sender is also considered. Mailbox providers assess the domain’s history, authentication practices (such as SPF, DKIM, and DMARC), and the overall sender behavior associated with the domain. A domain with a good reputation signals to mailbox providers that the sender is trustworthy and likely to deliver valuable content.

Consistency and Trust

Consistency in sending patterns, content quality, and subscriber engagement is essential for building and maintaining a positive sender reputation. When a sender consistently delivers relevant, non-spammy emails to engaged subscribers, it establishes trust with mailbox providers. This trust translates into improved deliverability rates, as mailbox providers are more inclined to deliver emails from reputable senders to the recipient’s inboxes.

Maintaining a positive sender reputation is vital for email deliverability. It requires consistent adherence to best practices, ensuring a clean sending history, and establishing trust with mailbox providers. By prioritizing engagement, authentication, and content quality, senders can enhance their sender reputation and improve the chances of their emails reaching the recipients’ inboxes.

Technical Elements and Email Configuration

To ensure that your messages reach the intended recipients’ inboxes, it’s important to understand the technical elements and email configuration factors that impact deliverability.

PTR Records and Sender Verification:

PTR records provide a reverse mapping between an IP address and its associated domain name. These records help mailbox providers verify the legitimacy of the sender. By setting up PTR records, you establish a connection between your domain name and the IP address from which you send emails. This email verification process enhances your email deliverability by building trust with mailbox providers.

Consistent Configuration:

Consistency in email configuration between your domain name and the IP address is crucial for effective deliverability. When you send emails, mailbox providers examine the alignment between the domain in the email header and the IP address used for sending. If there are inconsistencies or discrepancies, it can raise red flags and lead to potential deliverability issues.

To maintain a consistent configuration, ensure that:

  • SPF (Sender Policy Framework) is properly configured: SPF is an email authentication method that allows you to specify which IP addresses or servers are authorized to send emails on behalf of your domain. Setting up SPF records provides mailbox providers with information about authorized senders, improving deliverability and reducing the likelihood of your emails being flagged as spam.

  • DKIM (DomainKeys Identified Mail) is implemented: DKIM adds a digital signature to your emails, providing a way for mailbox providers to verify the integrity of the email content. It ensures that the email hasn’t been tampered with during transit. Implementing DKIM helps build trust and enhances deliverability.

  • DMARC (Domain-based Message Authentication, Reporting, and Conformance) is in place: DMARC combines SPF and DKIM to provide a policy framework for email authentication. It allows you to specify how mailbox providers should handle unauthenticated emails from your domain. Configuring DMARC records can improve email deliverability and protect your brand reputation. Test your SPF & DKIM records with our free tool. 

Sending From A Free Domain Email

Email marketers sending emails from a free domain email ID, such as Gmail, Yahoo, or Hotmail, can have a negative impact on email deliverability, as highlighted in source 2. When marketers use a different email ID other than their domain, it can compromise their sender reputation and increase the likelihood of spam filters flagging it.

Using a free domain email address for mass email campaigns can result in emails being marked as spam, wasting all the effort put into crafting the message. Revised DMARC policies have made it clear that sending mass emails from free email service providers can lead to deliverability issues.

To improve email deliverability rates, it is advisable to use an email ID associated with your company’s domain. This helps convey the legitimacy of the sender and builds trust with the recipients. For example, using an email address like [email protected] clearly indicates that the email is coming from your organization.

Using an email ID specific to your business can ensure good email deliverability rates, especially for global brands with multiple services and products. By aligning the email address with your brand, recipients can instantly recognize your emails and establish a stronger reputation for your domain.