18 June

Email deliverability demystified: Ensuring your emails reach the inbox

Olena Zinkovska
Olena Zinkovska Blog editor
Table of contents
  1. What is email deliverability?
  2. What is a good email deliverability rate?
  3. What affects email deliverability
  4. How to improve email deliverability: Best practices
  5. Email deliverability tools
  6. Wrapping up
What is email deliverability?

What is email deliverability? And why is it so hard to keep it high? In this article, you’ll find out what a good email deliverability rate is and what tools you can use to ensure your emails land in the desired inbox. From deliverability challenges to effective tips on how to overcome them — it’s all here, so let’s dive in.

What is email deliverability?

Email deliverability is also known as inbox deliverability or inbox placement. It determines where your email will end up being. Is it going to be a subscriber’s inbox, a spam folder, or some other folder? This being said, efficient email deliverability means the likelihood of your email reaching the right inbox is high.

What is the difference between email deliverability and email delivery?

While email deliverability is about where your email lands, email delivery is whether your email is accepted at all. In other words, a successful email delivery involves a receiving mail server approving an email from your service provider.

If an email is accepted, it can then end up in a spam folder or the inbox (this is all about email delivery). However, whether an email gets into a spam folder or instead successfully reaches the inbox — this is the scope of email deliverability.

Why does email deliverability matter?

Basically, email deliverability is essential for your company's success. No matter how perfect your content is, if it doesn’t reach your audience, what’s the point of all your hard work? The ability of your emails to reach the desired inbox is the cornerstone of improved customer relationships, boosted brand awareness, and better email ROI.

If a transactional email gets lost on its way, it might compromise the customer's trust, and as a result, they might abandon your product altogether. When it comes to marketing email campaigns, it’s crucial for your perfectly crafted offer to end up in the inbox. Your open rates will likely drop if emails land in spam.

What is a good email deliverability rate?

To estimate an email deliverability rate, we take the number of emails sent and calculate how many of them reached the inbox and how many of them ended up in a spam folder:

Email deliverability (%) = emails delivered to the inbox ∕ total number of emails sent ✕ 100

Say you’ve sent 50 emails, and only 37 of them reached the inbox. This gives us a deliverability rate of 74%.

According to EmailToolTester’s report:

  • any rate lower than 83% is considered poor;
  • rates between 83% and 88% are deemed acceptable;
  • deliverability rates above 89% are considered excellent.

or above is considered an acceptable or good email deliverability rate.

What affects email deliverability

Having figured out why email deliverability is important and how to calculate one, it’s high time to discover what might affect it. Let’s dive into the most common pitfalls one needs to avoid to ensure a high deliverability rate.

Non-set email authentication

Email authentication is among the most crucial elements influencing email deliverability. Proper email authentication protocols validate you as a trustworthy sender, improving the chances of your emails reaching the recipient.

In case your domain lacks email authentication, your emails might be considered illegitimate and spam, as you will seem less credible as a sender. It may also hurt your sender reputation, which is our next point.

Poor sender reputation

Trust is fundamental in email deliverability.

Keith Kouzmanoff

Keith Kouzmanoff,

Leading email marketing strategist.

The better your sender reputation, the higher the chances that your email will land in the recipient’s inbox. A poor sender reputation is one of the reasons your emails go to spam, so it hurts email deliverability considerably.

Among the factors affecting your sender reputation are:

  • lack of authentication;
  • blacklisted IP addresses, domains, or servers;
  • low-quality list of email addresses.

Email list low quality

To maintain high email deliverability and protect your sender reputation, consider these essential practices:

  • avoid buying or borrowing email contact lists, as this can lead to high bounce rates, low open rates, and poor engagement. And also, it’s against the rules;
  • stick to double opt-in, as 54% of recipients mark an email as spam if the sender did not ask for permission to send promo emails (we will discuss double opt-in in detail later);
  • regularly clean and segment your email list to ensure it remains up-to-date and targeted.

You might also like

Stripo_Featured Image_Cleaning Contact BaseEmail List Cleaning: Top 10+ Services

Use of the wrong tools for email sending and sending spam content 

Another factor affecting deliverability is how you send your emails. In other words:

  • the sender tools you use matter. Yes, the rating of your email marketing automation platform is also important, so it’s best to use trustworthy ones;
  • be sure to scan your content with an email spam checker to avoid compromising your sender reputation.

Poor user engagement, low quality of content and design

If you want to have a high deliverability rate, you need to tailor your content to the needs of your subscribers. From compelling subject lines to relevant and valuable content sent at the right time to the right audience — these are the elements that encourage your subscribers to open and engage with your emails.

According to Zero Bounce, 47% of subscribers say they open emails from brands because brands do send relevant content.


of subscribers open brand emails due to the relevance of the content.

Being blacklisted

Common reasons your email can get blacklisted:

  • high bounce rates;
  • spammy content in emails;
  • unsolicited bulk emailing (spam);
  • malware or phishing links within emails;
  • user complaints or high report rates.

You might also like

is-my-email-blacklistedIs my email blacklisted?

How to improve email deliverability: Best practices

Since we’ve covered the terms and challenges, let’s uncover what you can do to enhance your email deliverability and how you should do it. We’ve singled out best practices that have proven to work. So shall we?

Implement email authentication

There are three typical authentication protocols you can use to protect your domain and boost your reputation as a reliable sender:

  • SPF (Sender Policy Framework);
  • DKIM (DomainKeys Identified Mail);
  • DMARC (Domain-based Message Authentication, Reporting, and Conformance).

The idea behind all three protocols is validating your IP address, domain, or server as a trustworthy one. However, the way these protocols operate is different. Each protocol has particular factors affecting whether your email will be accepted or rejected. 

You might also like

deliverability-with-email-authenticationHow to improve deliverability with email authentication

Warm up your IP

If you don’t want your marketing campaign to be considered spam, always warm up your IP before starting a bulk campaign. To create and keep up the good reputation of your domain and IP address, you need to take things slowly. Increase the number of emails sent gradually, and most importantly, do it regularly.

In case your domain isn’t new but has been inactive for some time, it needs warming up as well. This way, a suspiciously huge number of messages after a pause won’t stain your sender reputation, and it will help you improve deliverability.

You might also like

Email_Deliverability_Stripo_Cover_ImageEmail Deliverability: Best Practices You Should Know

Maintain consistent sending of emails

Make sure your domain isn’t a pendulum swinging from no activity for a long time to hundreds of emails sent per day. Keep it regular, as being too active after a pause can be regarded as suspicious activity. Send emails consistently.

Choose a reliable email service provider

It’s no secret that different email service providers will have different deliverability rates. For this reason, it’s crucial to choose a reliable provider to ensure your email campaign won’t go down the drain.

Emailtooltester shared a list of the most reliable, in their opinion, email providers. But we also suggest that you ask your ESP for their numbers in case they have changed over time.

Clean and segment email list

As we’ve mentioned above, a clean email list is a must. Don’t hesitate to spend time compiling your email list, monitoring, and deleting inactive subscribers. Make sure you regularly check for invalid emails and remove them from the list.

Last but not least, segment your audience so that you can send targeted content that will reach the right recipients. 

You might also like

Email Segmentation_Strategies and Best Practices_Featured ImageThe power of segmentation: How to use email list segmentation to boost your ROI

Use double opt-in

Confirmed opt-in ensures your subscribers expect your emails, reducing the likelihood of them being marked as spam. Additionally, using double opt-in helps comply with international regulations such as the GDPR and the CAN-SPAM Act, which monitor unsolicited emails.

Send only solicited emails.

Personalize email content

Personalization matters. Send content based on a subscriber’s preferences and past interaction with a brand.

Carry out surveys and rely on analytics to find out data about subscribers’ interests so that you can tailor emails that are relevant and valuable. 

You might also like

personalization-in-email-marketing-bannerPersonalization in email marketing

Make unsubscribe easy

According to the Zero Bounce report, 49% of subscribers mark an email as spam only because the email does not have the “unsubscribe” option.


of subscribers mark emails as spam if they lack an "unsubscribe" option.

Each email should have a single-click unsubscribe link. This link should be easy to notice, so make sure it’s placed either in the header, footer, or even both. Don’t make it confusing — ensure it conveys a clear message like “Unsubscribe” just like the image below.

The unsubscribe button _ Email deliverability

(Source: Email from Stripo)

Avoid spam triggers

There is a list of words that are typically considered spam (because they are often used by spammers). You’re probably familiar with spam words such as “Free,” “Sensational,” “Hurry,” “Act now,” etc.

However, legitimate marketing campaigns might also need to use words that are known as “spammy.” What do you do then? If you know that a particular word can trigger a spam filter, run a spam check of your content to see your spam score. Even though some words trigger spam filters, if they’re naturally used in the right context, your spam score will be low.

Email deliverability tools

Last but not least, we’ve researched and singled out various deliverability tools with different features. Check out our list and find the best email deliverability service that is right up your alley.

  • Mailtrap — perfect for email authentication, checking spam scores, and detecting and removing spam triggers and malicious links;
  • SMTP2GO — an advanced tool for monitoring bounce rates, spam traps, and blacklists, as well as sending marketing emails with an in-built “unsubscribe” link.

Wrapping up

This comprehensive guide to email deliverability clarifies how you can ensure your emails consistently reach their intended inboxes. By understanding the factors that affect deliverability — from choosing the right tools and maintaining a reputable sender status to keeping your email lists clean and engaged — you can enhance your email strategy and, ultimately, your campaign’s success. Remember, a high deliverability rate not only protects your sender reputation but also boosts your ROI by ensuring your messages are seen by your audience.

Create professional emails with Stripo fast and stress-free
Was this article helpful?
Tell us your thoughts
Thanks for your feedback!
Stripo editor
Simplify email production process.
Stripo plugin
Integrate Stripo drag-n-drop editor to your web application.
Order a Custom Template
Our team can design and code it for you. Just fill in the brief and we'll get back to you shortly.

Stripo editor

For email marketing teams and solo email creators.

Stripo plugin

For products that could benefit from an integrated white-label email builder.