by Adam Kościelak Oct 19, 2021

Table of Contents

Email marketing is one of the most vital channels businesses can use to reach out to their audience. The fact that people signed up to your email list means they’re interested in what you have to offer. 

As a result, expect to generate high open and click-through rates from the emails you send, which means greater conversions and revenue moving forward. In fact, for every dollar spent on email marketing, you could be $42 richer, assuming that you observe the best email practices.

However, this is only possible if your emails are landing in your email subscribers’ inboxes. There’s a chance that the emails you’re sending go straight to the spam folder — if they’re even receiving them at all.

Aside from building a solid email marketing strategy and campaign, you also need to tighten the nuts and bolts of your operations. When it comes to sending emails, email deliverability should be at the top of your list. 

What is email deliverability?

Email deliverability refers to the ability to send emails to subscribers successfully.

Ideally, you want all the emails you send to arrive at their destination to maximize your ROI and revenue. However, according to EmailToolTester, the average deliverability rate is 85.3%. That means, out of five emails sent, an average of one email fails to arrive in the inbox. While approximately 15% of failed emails sent may seem like a small number to some, this adds up to thousands of emails that accumulate over time serve as missed opportunities for possible conversions.

The majority of email deliverability falls on the email platform you’re using. Email tools may share similar features, but their deliverability rates vary due to different factors, some of which we will discuss later.

To test email deliverability, these email service providers send emails from the dedicated IP addresses they're using to a test group of email addresses representing the top ISPs that their customers are sending to. The results should be able to give them a general idea of how many emails are successfully delivered.

From here, they can develop internal scores that measure email deliverability based on volume, spam complaints from recipients, and bad addresses, to name a few factors.

To help you verify the deliverability rates of your email campaigns, you can use tools to monitor your IP and domain reputation. As mentioned, the lower the sender score, the more people won’t receive your emails.

What impacts email deliverability?

There are a variety of factors that affect email deliverability. Below are some that you should be wary of:

Sender reputation

As mentioned, sender reputation determines how high or low your deliverability rates are. The goal is to increase your reputation on a level where most of your emails are sent to inboxes without a hitch. And to achieve this, you need to optimize your campaigns for the following variables:

  • Open rate - Get more people to open your emails once it lands on their inbox. Writing catchy and compelling subject lines ought to do the trick.
  • Email content - The content must match what was promised in the headline. Also, it should be in line with why people subscribed to your list in the first place. For example, if people signed up for your newsletter because they want to receive exclusive news and tips, make sure to send them more of these content types instead of promotions.
  • Recipient engagement - Aside from opening your emails, they should also take action by clicking on the links or buttons in each or replying to them.
  • Spam traps - These are emails that appear legitimate but are actually honeypots used to monitor spam emails. If you bought your email list or added scraped emails from a domain, you most likely have spam traps in your list. Having lots of spam traps in your list lowers your sender reputation.

Spam complaints

It’s possible that subscribers may mark your emails as spam. Below are some of the reasons why:

  • The emails you send aren’t relevant to your subscribers.
  • They don’t remember subscribing to your list probably because it may have been a while since you last emailed them.
  • They didn’t subscribe to your list and you’re sending them unsolicited emails.
  • Your emails are using spam trigger words.

Once you’ve accumulated spam complaints from your subscribers, expect your emails to go straight into their spam folders instead. To avoid this from happening, you must constantly send them relevant emails that interest them.

Poor list quality

Sometimes, the reason for low email deliverability is your subscribers. Some of those who signed up to your email don’t bother opening the emails they receive from you. Due to their inactivity, your sender reputation decreases.

However, most of the time, your email list becomes poor if you bought them and didn’t grow them organically. 

Email authentication

The recipients and their mailbox provider perform email authentication to verify the sender's identity. 

The top three methods of authentication include sender policy framework (SPF), domain keys identified mail (DKIM), and domain-based message authentication (DMARC). These are designed to complement SMTP, which is the most fundamental protocol applied for sending emails.

If the email you sent failed authentication using any of the methods above, it will be flagged or rejected by the mail server.

How to improve email deliverability 

Now that we’ve detailed the different factors that influence email deliverability and sender reputation, it’s time to discuss the various ways you can improve your rates. Below are some of the easier and more popular solutions you can implement in your campaigns moving forward.

Use double opt-in

As mentioned, a reason for low deliverability rates is due to inactive subscribers in your list. To prevent these types of subscribers from entering your list in the first place, you need to implement a double opt-in process in your email marketing tool.

When set up correctly, people who will sign up to your mailing list will receive an automated email from you confirming their subscription. They must open the email and click on the link so they can receive your marketing emails. If they don’t click on the link inside the email, they will remain unsubscribed and won’t receive the messages.

Unlike single opt-ins, double opt-in allows you to verify actual people who want to receive your emails. The fact that they opened your message to confirm their subscription is a testament to that. Also, it ensures that the email address people entered is correct. If they didn’t receive the double opt-in email, chances are they mistyped their address.

Build IP credibility

To fully understand how email deliverability works, you need to know how much spam internet service providers (ISPs) have to deal with through the years.

According to Statista, 45.1% of emails sent during March of 2021 are spam. The figure is the lowest since 2014, with 71.1% of emails labeled as spam at April 2014 as its peak.

The decrease in spam rate can be attributed to better spam filters resulting in a greater email delivery rate. 

And to bypass the spam filter, you must first improve the reputation of your dedicated IP address. To do this, you must start slow with your email campaign by sending only a handful of emails every month. 

Your goal is to get subscribers to engage with your emails. Once you’ve achieved good numbers according to your email analytics, you can gradually send more emails as you see fit.

Also, if you’re working your way out from getting your domain or IP address blacklisted, monitor its status using MxToolbox Email Blacklist Check while observing the best email practices. 

Maintain a consistent sender name

When sending emails, make sure to settle with either your real name or your brand. You can’t flip-flop between names as it goes against the CAN-SPAM act.

The best way to approach this is to use “[First Name] from [Brand]” as the sender. Replace [First Name] with the sender’s real first name and [Brand] with your brand name. 

This way, you not only put your brand at the forefront of every email, but you also associate it with a real person sending that email to recipients.

Send the right amount of emails

As the saying goes, “too much of something is bad enough.” The same thing applies to emails. You don’t want to go overboard and send subscribers emails by the hour. By annoying them with your emails, even if they’re well-written ones, you make them go sour on your brand and cause them to make your emails as spam and unsubscribe from your list.

However, when it comes to the best email marketing sending frequency, there is no magic number. While sending fewer emails may lead to greater engagement and conversions, the results vary depending on the niche or industry, the type of audience it is, the kind of campaign you’re running, and more.

Therefore, you need to refer to the analytics of your email service provider of choice. From here, you’ll be able to see the appropriate number of emails to send, depending on your campaign.

Give the option for subscribers to opt-out

If people want out of the list, there’s no point in keeping them there. You don’t want disgruntled subscribers constantly flagging your emails as spam and not engaging with them in a positive way because they can’t opt-out from your site.

Since the CAN-SPAM Act requires people to include an unsubscribe link in all commercial emails, it would be wise to do the same on all your messages.


If you want your email marketing campaign to be a rousing success, you must maximize email deliverability first. 

Attracting the right people as subscribers and writing relevant content in your emails are the first steps in doing so. Next, you need to monitor your analytics to see if the engagement rates of your email campaign are favorable so you can scale up with the frequency of emails you send. 

By maintaining this process and observing the other tips above, you can ensure that your subscribers receive your emails without fail.

About the author

Rebecca DiCioccio is a SEO Marketer for Paperform. Rebecca’s background in copywriting and keen interest in SEO and digital marketing mean she understands the importance of staying up to date with the latest trends in a dynamic and ever changing industry. Outside of work, Rebecca can be found exploring the outdoors, or with a book in hand.

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