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Email deliverability: Complete guide + best practices

Email deliverability: Complete guide + best practices

min read

In our hyper-connected world, email remains an integral part of personal, corporate, and marketing communication. However, the effectiveness of an email campaign depends heavily on a factor that often goes unnoticed: email deliverability. 

Understanding email deliverability, how it's measured, and how to improve it can significantly boost the success rate of your email campaigns. 

This guide will help you master this essential, yet often overlooked aspect of email marketing.

<a href="#email-deliverability" class="anchor-link">What is Email Deliverability?</a>
<a href="#track-deliverability" class="anchor-link">How Can You Track Email Deliverability?</a>
<a href="#good-deliverability-rate" class="anchor-link">What is a Good Email Deliverability Rate?</a>
<a href="#affects-deliverability-rate" class="anchor-link">What Affects Email Deliverability Rate?</a>
<a href="#improve-deliverability" class="anchor-link">Best practices to improve email deliverability</a>

<div class="anchor-wrapper"><div id="email-deliverability" class="anchor-target"></div></div>

What is Email Deliverability?

Email deliverability refers to the ability of an email to reach the recipient's inbox successfully without bouncing back or being marked as spam. It's not just about whether the email was sent successfully; it's about whether it was received and landed in the inbox, not in the spam folder.

a diagram showing the steps an email goes through when it's delivered

Deliverability depends on various factors, including the sender's reputation, the relevance and quality of the content, and the infrastructure used to send the email. All these aspects determine whether your email makes it to the recipient's inbox or ends up in their spam folder.

An email deliverability rate is calculated as a percentage, showing the proportion of emails that successfully reached recipients' inboxes out of the total emails sent. However, calculating email deliverability with absolute certainty can be challenging since you can't definitively determine if an email ended up in someone's spam folder. Remember, email delivery is not the same as email deliverability.

To gain a more accurate understanding, you can use email deliverability monitoring tools and services that simulate email placement in different email clients and spam filters, offering estimations and insights into deliverability performance.

It’s also important to focus on trends and patterns over time rather than relying on a single metric for a definitive calculation. You can track these patterns to see if your email deliverability is changing as you continue to engage with your email list.

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How Can You Track Email Deliverability?

Tracking your email deliverability rate can give you valuable insights into the effectiveness of your email campaigns. 

an illustrated data dashboard showing various email deliverability metrics

Here's how you can track email deliverability:

  • Delivery Rate: This is the percentage of emails that didn't bounce back and were delivered to the recipient's server. Just remember that a high delivery rate doesn't necessarily mean high inbox placement.
  • Bounce Rate: This includes both hard bounces (permanent delivery failures, usually due to invalid email addresses) and soft bounces (temporary delivery issues, like a full inbox). A high bounce rate can negatively affect your sender reputation.
  • Spam Complaints: These occur when recipients mark your email as spam. A high number of spam complaints can significantly affect your deliverability rate.
  • Open and Click-through Rates: Low open and click-through rates may indicate that your emails are not engaging or are being delivered to spam folders.
  • Spam Filter Testing: Tools like GlockApps and can help you test your emails against various spam filters to see if they're likely to be marked as spam.

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What is a Good Email Deliverability Rate?

Most email service providers (ESPs) will claim to offer an email deliverability rate at or above 95%. Generally, an excellent email deliverability rate is above 95%. This means that more than 95% of your emails successfully reach the intended recipients' inboxes. A rate below 90% usually indicates issues that need addressing in your email campaigns or sender reputation.

Keep in mind that while having a 100% deliverability rate might seem like the ultimate goal, it's not always feasible due to various reasons, such as hard bounces (permanent delivery failures), spam filters, or simply recipients accidentally providing incorrect email addresses.

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What Affects Email Deliverability Rate?

6 illustrations showing different factors that affect email deliverability

Several factors can impact your email deliverability rate:

  1. Sender Reputation: ISPs (Internet Service Providers) look at your IP and domain reputation to decide if your emails will reach inboxes or spam folders. Sending high volumes of spam or receiving many spam complaints can harm your sender reputation.
  2. Authentication Protocols: Protocols like SPF, DKIM, and DMARC (we’ll get into these below!) help ISPs verify your identity as a sender, reducing the chances of your emails being marked as spam.
  3. List Quality: A list full of non-existent, misspelled, or unengaged recipients can lead to high bounce rates and lower deliverability. Regularly cleaning your list and validating email addresses can improve deliverability.
  4. Content Quality & Schedule: The relevance and quality of your email content can impact deliverability. If your emails are flagged as spam or ignored by recipients, ISPs might start filtering out your messages.
  5. Engagement: ISPs track how recipients engage with your emails.

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Best practices to improve email deliverability

Now that we've inspected email deliverability from all angles, the real question is: how do you improve it? 

Optimizing email deliverability is more than just avoiding spammy practices; it's about building a robust and reputable email program that delivers value to its recipients. 

This guide provides best practices and tools that you can incorporate into your email strategy today. Whether you're a small business owner just starting your email marketing journey or a seasoned marketer looking for ways to improve your email deliverability, these tips are designed to guide you towards achieving superior inbox placement and ultimately, successful email campaigns. 

a checklist for improving email deliverability

Create and maintain a quality email list

Building a quality email list is a fundamental aspect of successful email marketing and plays a crucial role in email deliverability. A quality email list consists of engaged subscribers who have willingly opted in to receive your communications. By focusing on quality over quantity and adhering to best practices, you can improve email deliverability rates, maintain a positive sender reputation, and ensure that your messages reach the intended recipients' inboxes. 

Build a quality email list

Building a quality email list for email marketing involves employing effective email capture strategies to attract engaged and interested subscribers.

A common approach is to offer valuable content or incentives in exchange for email sign-ups. By providing something of value, such as exclusive content, discounts, or free resources, you can entice individuals to willingly share their email addresses. 

Although purchasing email lists may seem like a quick and easy way to increase the reach of your email marketing campaigns, these lists often contain spam traps, old addresses, and recipients who have not opted-in to your emails. Sending to these lists can damage your sender reputation.

Implement double opt-in

Double opt-in is a two-step process that verifies email subscribers' intent. After the initial sign up, a confirmation email is sent, asking recipients to confirm their subscription by clicking a unique link or button. 

This process ensures explicit consent, filters out fake addresses, reduces spam complaints, and improves deliverability and engagement rates.

Regularly prune your email list, bounce rate

Pruning an email list for email marketing involves regularly removing inactive or unengaged subscribers. It is done to maintain a high-quality list and improve email campaign performance. 

Sending emails to engaged recipients who are genuinely interested in your content helps increase deliverability and by removing inactive subscribers you can reduce bounce rates, lower spam complaints, and enhance deliverability rates.

Pruning also helps optimize resources by focusing on the audience most likely to convert and engage with your emails. Regularly evaluating and removing unengaged subscribers allows you to nurture a more responsive and targeted email list.

Segment your email list

Email list segmentation is the practice of dividing your email subscriber list into smaller, more targeted segments based on specific criteria such as demographics, interests, or engagement levels. 

Segmentation allows you to send more relevant and personalized emails to different groups within your audience. By tailoring your messaging to the specific needs and preferences of each segment, you can improve engagement, open rates, click-through rates, and overall campaign performance.

Include an unsubscribe link

Including an unsubscribe link in your emails is crucial for email deliverability. The ability to unsubscribe provides recipients with a clear and convenient way to opt out of receiving further emails, respecting their preferences and privacy. 

Giving your recipients an option to unsubscribe also helps reduce the chances of recipients marking your emails as spam. Not only does this help increase your sender reputation, but you’ll also enhance trust and transparency with your subscribers.

Finally, compliance with regulations like the CAN-SPAM Act and GDPR mandates the inclusion of an unsubscribe link in commercial emails. Overall, including an unsubscribe link promotes good email practices and contributes to better deliverability and engagement.

Let recipients tell you their preferences

Allowing subscribers to choose their email preferences, including the frequency and type of emails they receive, helps maintain engagement and reduces the chance of being marked as spam.

This may allow subscribers to indicate what kinds of emails they’d like to receive, like regular newsletters, promotions, or blog posts sent to their inbox. You can also give the option to receive emails daily, weekly, or less frequently.

Boost your reputation

Email sender reputation refers to the perception and evaluation of a sender's credibility and trustworthiness by Internet Service Providers (ISPs) and email recipients. It is based on various factors, including engagement rates, spam complaints, bounce rates, and adherence to email best practices. 

A good sender reputation is crucial for achieving high email deliverability rates and ensuring that emails reach recipients' inboxes rather than being filtered as spam. Maintaining a positive sender reputation requires consistent, relevant, and engaging email campaigns while avoiding practices that could harm reputation, such as sending to purchased lists or engaging in spammy behavior.

Use a reputable email service provider (ESP)

An Email Service Provider (ESP) is a platform or service that enables businesses to send, manage, and track email campaigns at scale. It provides the necessary infrastructure, tools, and features to create, automate, and analyze email marketing efforts. 

Using a reputable ESP is crucial for several reasons. They often offer robust features for list management, segmentation, and personalization, allowing you to achieve targeted and effective email campaigns. Reputable ESPs also prioritize data security and compliance with regulations, ensuring the protection of sensitive customer information.

Providers like Mailchimp, SendinBlue, and Constant Contact have built their reputations on good delivery rates. They have relationships with major ISPs and may help you work to resolve deliverability issues. 

You can also leverage the security and reputation of Google by sending personalized mass emails using Streak’s mail merge feature in Gmail.

Use a reputable IP address

An IP address, or Internet Protocol address, is a unique numerical identifier assigned to devices connected to a network. The reputation of the IP address from which emails are sent plays a crucial role for email deliverability.

Monitoring IP reputation through tools like Sender Score helps track the health and deliverability of your emails. Maintaining a good IP reputation involves sending relevant, engaging content, avoiding spam complaints, and adhering to email best practices.

Authenticate your emails

Implementing email authentication protocols like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) adds credibility to your emails and helps protect against spoofing.

SPF (Sender Policy Framework):

SPF is an email authentication method that allows the owner of a domain to specify which IP addresses or mail servers are authorized to send emails on behalf of that domain. It works by publishing a DNS (Domain Name System) record containing a list of approved senders for the domain. When an email is received, the recipient's mail server checks the SPF record to verify that the email comes from an authorized source. If the sending IP or server is not listed in the SPF record, it may be considered suspicious and treated as potential spam.

DKIM (DomainKeys Identified Mail):

DKIM is another email authentication technique that uses digital signatures to verify the integrity of the email message. It works by adding a digital signature to the email's header using cryptographic techniques. The sending server signs the outgoing email with a private key, and the recipient's server can then verify the signature using a public key published in the DNS records of the sender's domain. If the signature is valid, it indicates that the email has not been tampered with during transit and that it originated from the claimed domain.

DMARC (Domain-based Message Authentication, Reporting, and Conformance):

DMARC is an email authentication and reporting protocol that builds upon SPF and DKIM. It allows domain owners to set policies for how email receivers should handle emails that fail SPF or DKIM checks. With DMARC, domain owners can specify whether such emails should be rejected, marked as spam, or allowed through. Additionally, DMARC enables domain owners to receive reports from email receivers about the status and disposition of emails sent using their domain. This feedback loop helps domain owners identify potential issues with email deliverability, spoofing, or abuse.

Collectively, SPF, DKIM, and DMARC work together to provide a robust framework for email authentication and help prevent email spoofing, phishing attacks, and unauthorized use of domain names. Implementing these protocols increases the chances of emails being delivered to the intended recipients' inboxes and reduces the risk of them being marked as spam or phishing attempts.

Send emails on a consistent schedule

Regularly sending emails (but not too frequently) can build your sender reputation over time. 

Test and analyze engagement metrics to find a consistency that works best for your audience. You can experiment with different days and times to identify when your audience is most active and responsive, and use data-driven insights to determine the optimal frequency for sending emails that maximizes open rates, click-through rates, and overall engagement.

Avoid sending too many emails

While sending emails consistently can help boost your reputation, excessive email frequency can lead to email fatigue and disengagement, causing recipients to ignore or unsubscribe from your emails. Overwhelming subscribers with a high volume of emails can be perceived as spammy or intrusive, damaging your sender reputation. 

To find the sweet spot, maintain a balanced and reasonable email frequency and focus on quality content. Ensure that each email provides value and maintains a positive relationship with your subscribers.

Monitor and avoid blacklists

Various organizations keep track of IP addresses known for spamming. Being listed on blacklists or triggering spam filters can significantly impact your deliverability. If your IP is on one of these lists, your emails will likely be blocked. 

You can use tools like MX Toolbox to monitor your IP status. If you find your IP address is blacklisted, take immediate action to resolve the issue. 

Start by identifying the blacklist and investigating the reason behind the listing. Address the underlying problem, such as improving email practices or addressing security vulnerabilities. Submit a delisting request to the respective blacklist, providing necessary information and demonstrating corrective actions taken. Monitor your IP reputation and email deliverability closely after requesting delisting.

Although it’s possible to be removed from a blacklist, it’s best to avoid it in the first place. Prevention is key, so regularly monitor your sender reputation and follow email best practices to minimize the risk of blacklisting.

Create great, easily accessible content

Spam filters analyze the content of your emails to determine their legitimacy. Using spammy language, excessive use of images, or misleading subject lines can harm your deliverability.

Maintain low complaint rates by using the tips below to only send relevant, high-quality content.

Personalize your content

Personalizing email content goes beyond simply using a subscriber's name or personal information. 

To create high-quality personalized emails, start by segmenting your email list based on demographics, interests, or past interactions. Use these segments to tailor the content to their specific needs and preferences. For example:

  • Incorporate dynamic content, such as product recommendations or personalized offers, based on their browsing or purchase history. 
  • Leverage behavioral data to send targeted emails triggered by specific actions or events. 
  • Craft compelling subject lines and compelling calls-to-action that resonate with each segment. 

By leveraging data-driven personalization techniques, you can create highly relevant and engaging emails that foster stronger connections with your subscribers and drive better results.

Reach out to new list subscribers promptly

Reaching out to new email subscribers promptly establishes a positive initial impression and helps set expectations. By engaging with subscribers early on, you can deliver relevant content while their interest is high, fostering a stronger connection. 

Prompt outreach also reduces the risk of subscribers forgetting about your emails or marking them as spam due to lack of recognition.

Avoid spammy language

Using spammy language, excessive use of images, or misleading subject lines can harm your deliverability. Not only are your subscribers more likely to mark your emails as spam, but the recipient’s ESP may filter out content that it recognizes as spam, sending it directly to their spam folder. 

Certain words and phrases can trigger spam filters. Avoid using phrases like "free," "guarantee," or "no obligation" in your subject line and email content. Instead, stick to language that promotes clear communication and delivers value, rather than trying to trick a recipient into clicking on your email in their inbox.

Use a recognizable sender name

Make sure your recipients know who the email is coming from. If they don't recognize your name, they might mark your email as spam.

Securing a custom email domain for your business can help recipients instantly identify your email in their inbox and further build your reputation. 

Using no-reply emails for email deliverability is not recommended because it discourages recipient engagement, prevents two-way communication, and can lead to higher spam complaints and lower overall deliverability rates.

Avoid large attachments

Large attachments can cause delays in delivery, as the larger file size requires more time to transmit. Recipients with limited storage may struggle to receive or access emails with large attachments, resulting in a poor user experience. Furthermore, large attachments consume additional bandwidth and resources, straining both the sender's and recipient's email systems.

Additionally, large attachments may trigger size limitations imposed by ISPs, leading to rejected or blocked emails. Spam filters often scrutinize emails with large attachments, increasing the likelihood of being flagged as suspicious or spam. 

Balance image-to-text ratio

Maintaining a balanced image-to-text ratio in emails is important for email deliverability. 

While there is no hard and fast rule, a general guideline is to aim for a ratio of approximately 60% text to 40% images. This is because relying too heavily on images can raise red flags for spam filters, as they may interpret image-heavy emails as potentially suspicious or promotional in nature. 

Including sufficient text ensures that the email content is accessible to recipients even if images are blocked or don't load properly. It also provides more context for spam filters to assess the email's legitimacy. 

Striking the right balance between images and text improves the chances of your email reaching the inbox and effectively conveying your message to recipients.

Test your emails for deliverability

To test emails for deliverability, you can utilize email testing tools and services like GlockApps that provide comprehensive previews across various email clients, devices, and spam filters. 

These tools allow you to assess how your email will appear to recipients and detect potential issues that might affect deliverability. Additionally, you can conduct deliverability tests by sending test emails to different email addresses and monitoring their delivery, ensuring they land in the inbox rather than being flagged as spam. 

Analyzing email metrics, such as open rates, click-through rates, and bounce rates, can also provide insights into deliverability performance.

Focus on building strong relationships

When it comes to email deliverability, there are no shortcuts or quick fixes. Trying to cheat or manipulate the system will only harm your efforts in the long run. 

The best approach is to focus on building a solid reputation with your subscribers and consistently delivering high-quality content. By engaging with your audience authentically, respecting their preferences, and adhering to email best practices, you can establish trust, foster meaningful connections, and improve your email deliverability rates. 

Remember, the path to successful email delivery lies in building a strong foundation of trust and consistently delivering value to your subscribers. So, invest the time and effort to cultivate that reputation, and watch as your email campaigns thrive and reach their intended audience.

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