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Key takeaways from Mailgun’s State of email deliverability 2023

Email deliverability is a niche topic that blends technical knowledge and marketing strategy. Find out what a global survey reveals about what senders really know concerning the best practices connected to landing in the inbox.



Why do some emails reach the inbox, some land in spam, and others are blocked from delivery? What can you do to improve your chances of getting messages into the inbox?

If you’re like many of the senders who took our email deliverability survey, you might think you already have the answers. However, the more you dig into the topic of deliverability, the more you realize how complex and nuanced it really is. Once you see the connection between deliverability and your return from investing in email, you’re going to want to know more.

Our exclusive report reveals that senders believe the biggest benefit of prioritizing email deliverability is customer satisfaction. In fact, more than 40% of senders around the world told us that’s why they focus on improving inbox placement. Bottom line? Your messages matter to customers and users.

More than 1900 professionals around the world answered our questions about everything from infrastructure and authentication to list building and measurement. Let’s take a look at some of the key findings in our report, The state of email deliverability 2023.

Top takeaways from our email deliverability survey

We’re about to dive deep into the world of email deliverability and uncover how senders feel about complex topics such as inbox placement testing, blocklists, and email list building. But before we jump in, here are some findings that are a bit of a wakeup call:

  • Even though senders say staying out of spam is their biggest challenge, only 16.4% are actively monitoring inbox placement.

  • To support deliverability, more than 60% of high-volume email senders are separating transactional and commercial messages on different IPs or domains.

  • 37.8% of those surveyed admit they are Not monitoring sender reputation with solutions like Google Postmaster Tools and Microsoft SNDS.

  • Nearly 32% of respondents who’ve been blocklisted recently say a Bad sender on a shared IP is to blame, making it the most-common reason.

  • Close to 28% switched to a dedicated IP after the blocklisting.

  • While 27.4% of senders conduct list hygiene Monthly or more, 38.7% Rarely or Never do so.

Over-confidence and uncertainty around inbox placement

When asked how well they understand email deliverability strategies, less than 20% of respondents said they were either Somewhat unconfident (13.3%) or Very unconfident (5.8%) in their knowledge.

While 15.7% of the senders we surveyed felt Very confident in their knowledge of deliverability, the greatest percentage were either Somewhat confident (39.8%) or Neutral (25.4%) on the topic.

Chart on confidence in email deliverability knowledge

Here’s the problem with being stuck in the middle: What you don’t know about email deliverability could easily hurt your business.

The negative effects of failing to understand what impacts inbox placement may be holding your efforts back and reducing email ROI in ways that you don’t even realize. So, if you think you know enough about staying out of the spam folder, the truth may surprise you.

Because email deliverability is broad and technical, our survey questions often let respondents say they were “Unsure” of the answer. The results revealed significant uncertainty in many key areas:

  • Nearly 25% are unsure if they’d been blocklisted in the last two years.

  • Among those using DMARC for authentication, 40% don’t know what their policy is.

  • More than 20% are unsure if they’re using a double opt-in for list building.

  • Around 27% of senders can’t describe their email sending infrastructure.

In many cases, it is smaller companies with low sending volumes that have the uncertainty... but not always. Gaps in knowledge around deliverability at the enterprise level may be related to the fact that different people in the organization have specific responsibilities involving email.

For example, IT professionals are most likely to make email sending infrastructure and technology decisions while the marketing team decides how to build and manage the database of contacts. IT specialists will set up email authentication protocols while marketers are the ones monitoring levels of email engagement. All these things can impact your ability to reach the inbox. But depending on your job title, you could be unaware of what’s happening.

To truly maximize efforts to improve inbox placement, technical and marketing teams need to communicate and work together. Mailbox providers like Gmail, Outlook, and Yahoo Mail pay attention to both technical and marketing factors to establish your sender reputation. If that reputation gets damaged, your emails are more likely to get filtered into spam.

The ups and downs of email deliverability

We asked respondents to rank their top three email deliverability challenges and the issue they ranked the highest was Staying out of the spam folder. Even though email authentication setup and regulatory compliance may be complicated, it’s the ongoing struggle of landing in spam that keeps most senders up at night.

Getting more emails delivered and Staying off email blocklists rounded out the top three challenges.

What do senders call their top deliverability challenges?

  1. Staying out of the spam folder

  2. Getting more emails delivered

  3. Staying off email blocklists

  4. Reducing email bounces

  5. Maintaining list hygiene

  6. Low subscriber engagement

  7. Improving sender reputation

  8. Complying with regulations

  9. Setting up email authentication

The benefits of improving inbox placement

Even though there seems to be plenty of uncertainty around how email deliverability works, most senders in our survey say their organizations place a high priority on landing in the inbox. So, where do they see a return on investment (ROI) from prioritizing deliverability?

When asked to choose the biggest benefit, more than 40% said a focus on deliverability helps generate Improved customer satisfaction. That was by far the most popular option. It was followed by the benefits of Increasing revenue from email (18.6%) and Reaching more leads and prospects (13.3%).

Bar graph shows 0% of senders say improved customer satisfaction is the biggest benefit of deliverability.

If more messages reach the inbox, it’s obvious that you have a better chance of making more money from an email campaign. It’s just as plain to see why high deliverability is better for converting more leads into customers. But what about customer satisfaction?

The reason this particular benefit lands at the top of the list is because email communication is a crucial part of the customer experience.

Much of that experience involves transactional emails, which often contain important information such as password resets and order confirmations. When those emails go missing, people notice, and it causes dissatisfaction. However, special promotions, product news, and email newsletters are also part of the customer experience. People subscribed to your list because they actually want your emails. You need to make sure those messages reach the inbox.

Download the full Forrester TEI study

What’s the real ROI of Sinch Mailgun?

Choosing the right technology partner is a huge decision, especially when it concerns something as important as email communications. Find out what a Forrester Total Economic Impact study reveals about how senders and partners see a significant return on investment from working with Mailgun.

Measuring deliverability and inbox placement

The delivery rate is one of the most basic and essential metrics for measuring email deliverability. While it does not tell the entire story, it depicts the percentage of messages sent that are ultimately accepted by receiving mail servers.

The comparison table below shows benchmarks for transactional and marketing email delivery rates. It also illustrates how mailbox providers may treat transactional email communication differently than marketing messages – even if they come from the same sender. This is why high-volume senders often send different types of emails from different domains or IPs.

Tran­sactional emai­ls

Mark­eting emai­ls

Tran­sactional emai­ls

Deli­very rate­ of 95% or high­er (4­7.1%)

Deli­very rate­ of 95% or high­er (2­7%)

Mark­eting emai­ls

Deli­very rate­ of 85% to 94% (1­9.3%)

Deli­very rate­ of 85% to 94% (2­4.2%)

Deli­very rate­ of 75% to 84% (7­.5%)

Deli­very rate­ of 75% to 84% (1­0.1%)

Deli­very rate­ belo­w 75% (5­.9%)

Deli­very rate­ belo­w 75% (1­1.2%)

Unsu­re of deli­very rate­ (2­0.2%)

Unsu­re of deli­very rate­ (2­7.5%)

Don’t be fooled by delivery rate percentages between 80% and 90%. They may not be as strong as they seem. For example, if you have an 85% delivery rate for transactional emails, that means as much as 15% of your customers could be missing important emails. Lower-than-normal delivery rates could also be a sign that you’re on a major blocklist or that your list contains a lot of invalid contact data.

Deliverability experts at Sinch Mailgun say every sender should aim to get as close to a 100% delivery rate as possible.

“For pure transactional email traffic, I would expect a 99% delivery rate and never much below that. For marketing emails, I think you should always aim for at least 95%. If you aren’t achieving that, you need to take a closer look at your program and practices right away.”

Alexandre Zibrick, Compliance and Deliverability Engineer, Sinch Mailgun

Of course, there are many other metrics connected to email deliverability. That includes standard email marketing metrics like open rates and click rates. These metrics help you understand how well your list is engaging with email content, which has a direct effect on your sender reputation. A sudden dip in opens and clicks could also be a sign that more emails are landing in spam than usual.

We asked senders in our survey to identify all the deliverability metrics they actively monitor. The delivery rate, opens, and clicks topped the list. Not far behind were measurements for bounces, unsubscribes, and spam complaints. But it’s a metric that landed lower on the list that senders should care about most.

Chart on email deliverability metrics

Only 16.4% of survey respondents say they are actively monitoring Inbox placement. Your inbox placement rate is arguably the most important deliverability metric. That’s because, unlike the delivery rate, it gives you an idea of how mailbox providers are filtering the messages you send.

The biggest misconception about email deliverability

That brings us to what is probably the most widespread misunderstanding in email deliverability...

Your delivery rate is not your deliverability rate. Technically speaking, there is no such thing as a deliverability rate. The closest thing would be the inbox placement rate metric.

Here are the formulas for these two metrics:

Delivery rate % = (# of messages delivered ÷ # of messages sent) X 100 Inbox placement rate % = (# of messages in the inbox ÷ # of messages delivered) X 100

The delivery rate measures the percentage of emails that receiving mail servers accept, but it does not take into account how they are filtered. Messages that land in spam are included in your overall delivery rate. That’s why inbox placement tells you so much more about deliverability.

The tricky part is finding ways to calculate inbox placement. How do you get inside contacts’ mailboxes and see how messages get filtered? The truth is – you have to predict it using a process known as inbox placement testing.

To conduct inbox placement testing, you need a seed list and seed mailboxes that you or a technology partner like Sinch Mailgun own and can access. These email addresses are not on your list. They’re only used for testing and should cover a variety of major mailbox providers.

Report for inbox placement statistics

An inbox placement test reveals the likelihood of your message being filtered to spam or landing in the main inbox. You can use inbox placement reports to identify and fix deliverability concerns before launching a campaign or sending triggered transactional messages. It’s also the best way to track deliverability improvements over time.

“People may not even be aware that there are ways to track the inbox placement rate. It’s not a metric that can be measured in the traditional sense.”

Nick Schafer, Sr. Manager of Deliverability and Compliance, Sinch Mailgun

The impact of blocklisting

Our report on email deliverability contains an entire chapter about blocklisting. An organization’s messages may get added to an email blocklist when mailbox providers notice patterns that indicate spammy or malicious sending behaviors. While being blocklisted doesn’t necessarily mean the sender did something wrong, it’s still a situation that needs to be dealt with.

The survey found that around 19% of the 1900+ senders in our survey had been placed on a blocklist in the last two years. Nearly 25% weren’t sure if they’d been blocklisted recently or not.

As for those who know they’d been blocklisted, we wanted to find out more about the ways senders handled the situation and how it affected them. For starters, it takes most companies a matter of days to get removed from a blocklist. More than 60% said they were delisted within one week.

Chart on blocklist remediation time

However, even if it’s only a portion of your email traffic that gets disrupted for a day or two, a blocklisting can still have a significant impact on your business. Remember, Improving customer satisfaction and Increased revenue from email were the biggest benefits of prioritizing deliverability. So, it makes sense that the opposite is true when deliverability goes wrong.

Senders who’ve been blocklisted told us the biggest negative impact was Delays for important messages (33.7%). That’s followed by 22.1% who chose Dissatisfied customers and another 15.9% who selected Lost time/productivity. More than 12% said the biggest impact was a Loss of revenue from email.

Chart on the impact of blocklisting

When we asked respondents how they ended up on a blocklist, 15.7% were Unsure what went wrong. But the most common reason senders believed they were blocklisted is due to a Bad sender on a shared IP (31.9%). Spam complaints and spam traps combined made up 24% of the responses.

Chart on reasons for blocklisting

When you send from a shared IP address, as many smaller senders do, you also share the IP reputation of others using it. So, if a spammy sender sharing your IP address starts blasting out unsolicited emails, it could reflect poorly on your reputation as a sender.

That’s why Sinch Mailgun adheres to a comprehensive Acceptable Use Policy (AUP). This is an agreement we have with customers who use our shared IPs. It sets expectations and benchmarks for being a responsible sender with a good reputation. The AUP protects our users by keeping bad senders off the Mailgun platform.

The most common changes to sending practices after a blocklisting were:

  1. Switched to a dedicated IP (27.8%)

  2. Started blocklist monitoring (27.3%)

  3. Chose a new email service provider (23.1%)

Our in-house experts say the behavior of bad senders can certainly be an issue. But if you deny the fact that you’re responsible for getting blocklisted, your deliverability problems will follow you.

“A shared IP will obviously have its risks. With dedicated IPs it’s different because it’s your responsibility, and if you’re unsure why you’ve been blocklisted, it probably comes down to your list building, list hygiene, or sending practices.”

Ashley Rodriguez, Deliverability Engineer, Sinch Mailgun

Building and maintaining email lists

The health and hygiene of your email list can have a direct effect on email deliverability. Unfortunately, our survey found there are still too many senders who fail to follow best practices while others are using questionable list building strategies.

One of the fastest ways to get blocklisted is to send mail to a spam trap. These are basically fake email addresses that mailbox providers and blocklists use to trap spammers. Since they aren’t real contacts, if you send to a spam trap address, you are almost certainly a spammer.

Spam traps may end up on email marketing databases when companies purchase lists of contacts or scrape the web for email addresses they can add. Our survey revealed a surprising number of senders are engaging in these dangerous list building practices. Beyond getting blocklisted, these acquisition methods could also violate privacy laws like GDPR.

Just as concerning were results showing that many senders fail to use list building practices that support a clean database with contacts who’ve given explicit consent to receive emails and are more likely to engage.

Our survey found only 26.7% of respondents are using a double opt-in when collecting new contacts for their email lists. A double opt-in involves an extra step before a new address is added to your email list. First, new subscribers must click a link in a confirmation email, which solidifies their intent to sign up and their consent to receive emails.

Double opt-in usage chart

In our report, deliverability expert Nick Schafer went as far as saying he believes every sender should be using a double opt-in. Yet, more than 52% of those we surveyed admit they are not while another 21.2% are Unsure.

Another best practice for email list hygiene is the use of a sunset policy. With this strategy, you proactively remove contacts who stop engaging with your emails. Or, you can have a policy that reduces the sending frequency to contacts who are less engaged. This practice protects your sender reputation by ensuring overall engagement rates stay high.

However, only 22.5% of senders in our survey say they are using a sunset policy. Nearly 60% admit they don’t have a policy in place while almost 18% are Unsure if sunsetting unengaged subscribers is part of their strategy.

Sunset policy usage chart

A sunset policy is one of several methods that support good list hygiene. Just as your body will have issues (and start to stink) with poor personal hygiene, you’re bound to have problems with your email program if you ignore list hygiene.

Many senders in our survey told us they are conducting list hygiene on a regular basis. In fact, 27.4% do it monthly or even more frequently. But there’s another side to the story. A combined 38.7% of respondents admit they Rarely or Never conduct list hygiene.

Chart on list hygiene frequency

At a minimum, you should conduct some list cleaning once or twice per year. There are also automated solutions, which can help you keep your list clean and healthy. That includes tools that can verify email addresses across your list or validate new contacts at the point of signup.

Our survey found that more than half of senders are not using tools to automate email address verification. That’s a missed opportunity. Invalid contact data, such as a typo in an email address, means you may not be able to reach a new customer or prospect. And if your list gets cluttered with too many of these invalid contacts, it will eventually damage your reputation and hurt deliverability.

That’s why Sinch Mailgun provides Email validation, which includes tools for real-time validation as well as a way to verify your entire list of contacts. Senders who use this solution have seen their bounce rates decline by more than 20%.

Clear up confusion around email deliverability

Out of the nearly 2,000 people who took our survey, only about 4% described their job role as “Deliverability Specialist.” It’s uncommon to have people who are totally dedicated to the many elements connected to landing in the inbox. Thankfully, there are powerful tools and knowledgeable experts out there making email deliverability less of a mystery.

Sinch Mailgun offers solutions that help senders optimize email deliverability. That includes ways to monitor blocklists and your sender reputation as well as tools for testing inbox placement and verifying email addresses. You can even preview how HTML emails render on different clients and devices before you send them.

You’ll find an entire suite of deliverability tools are at your disposal. And it’s worth it. A Forrester Total Economic Impact (TEI) study suggests organizations could see a 264% ROI after just a few years working with Sinch Mailgun.

If you see the value of prioritizing inbox placement, our Deliverability Services connect you with technical experts who can answer all your questions and work with you to develop a custom plan.

Are you staying out of the spam folder?

The state of email deliverability 2023

Dive deeper into email deliverability with more from our exclusive report. Find out what hundreds of senders around the world are doing to reach the inbox and hear from experts who’ve spent their careers navigating this complex topic. Explore the insights now. No form filling required.

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