Email marketing deliverability: Key takeaways from Road to the inbox 2025

Key email marketing deliverability statistics

In our survey, we heard from more than 1,100 people who are connected to email sending in their organizations. Here are some of the biggest takeaways from the research. Check them out, and then we’ll dive deeper into the results to explain what it all means for your email marketing strategy.

Email marketing ROI and deliverability

You’ve probably heard how email is a digital customer communication channel with an extremely high return on investment (ROI). It’s an effective way to deliver timely, relevant, personal messages to your customers and subscribers.

Of course... that’s only true if your emails reach the inbox. When they get blocked or land in spam, the channel becomes much less effective. As your email deliverability goes, so goes your email ROI.

That’s why many email senders in our survey place a priority on achieving inbox placement. 78.5% say good deliverability is important to their organizations, rating it an 8 out of 10 or higher.

Getting a return on your investment isn’t the only reason to improve email marketing deliverability. Here’s a quick look at what our survey found to be the top three benefits of reaching the inbox and the three biggest problems with being filtered into the spam folder.

These results make it clear – email is crucial to the customer experience. The biggest benefits and problems center around reliable customer communications. But reaching the inbox can also affect how contacts view your brand and whether or not they’re happy with the customer experience you’re delivering.

How your email list impacts inbox placement

The marketing team is usually in charge of growing the email list as well as managing those contacts after they opt in. List building and list hygiene are two factors that directly affect email deliverability.

While there are many senders in our survey who understand this, there’s also plenty of room for improvement. Let’s start with list building...

Close to 10% of survey respondents admit that they’ve used shady tactics to build their lists in the last two years. That includes buying email lists and using software to scrape the web for email addresses. While 10% might seem like a small percentage, it’s a big problem.

Why are these tactics bad ideas? There are quite a few reasons, and they all relate to the fact that these senders failed to get permission from those new contacts.

• If you email people without consent, you could be violating GDPR.

• Emailing people who don’t opt in will increase your spam complaint rate.

• Since these contacts never asked for your emails, your engagement rates will suffer.

• These tactics can also lead to damaging spam traps on your email list.

• Sending to spam traps and emailing people without consent could get your domain blocklisted by major mailbox providers.

A good email strategy should be based on the concepts of permission-based marketing. It’s an agreement between you and your subscribers that you’ll send them what they signed up for, and they can unsubscribe when they choose.

An effective strategy for building a list of contacts who truly want to hear from you is the double opt-in method. This is when you send an initial email to new contacts asking them to click and confirm their intent to subscribe.

Our survey found close to 40% of email senders are using a double opt in, but almost 48% say they do not and more than 12% are unsure.

While a double opt in could mean your email list doesn’t grow as quickly, it protects you from the perils of poor engagement (more on that later). The double opt-in process also helps with list hygiene because it keeps invalid email addresses out of your database.

Speaking of list hygiene, how often do you clean up your contact list? Our research found around 60% of senders conduct list hygiene on a regular basis, including almost 27% who do it monthly or more. Unfortunately, close to 40% of those we surveyed say they rarely or never conduct list hygiene.

List hygiene includes periodically removing outdated, invalid, and inactive contacts from your list. You can also segment unengaged subscribers and send to them less often. Sinch deliverability experts say skipping list hygiene stinks, and it’s a major missed opportunity.

“Good list hygiene might be one of the things everybody forgets about, but it is so key to your success, and it’s something that can easily be done. You’re investing time and money into sending emails, and you want to make sure you’re taking care of the easiest things possible.”

Ashley Rodriguez

Deliverability Engineer II, Sinch

Email engagement and your sender reputation

Sender reputation is a score that mailbox providers give to the domains and IP address from which emails are sent. They’re asking, “Do these emails come from a responsible sender that our users want to hear from?”

If the answer is “Yes”, you’ve got a good chance of making it to the inbox. If it’s not, you’re more likely to be filtered into spam.

One of the best ways to show that your emails are wanted is to get good email engagement. That means your contacts are opening what you send, spending time with the message, and clicking on the links inside your emails.

However, when we asked survey participants to choose the factors they believe help improve or repair sender reputation, only 15% chose increasing email engagement. Respondents were more likely to choose list hygiene, reducing spam complaints, and reducing bounce rates (as well as several other options).

The truth is – all of the factors listed above can affect your sender reputation. However, when your contacts engage with your emails, it sends strong, positive signals to mailbox providers that your emails are wanted and can be trusted.

Improving email engagement relies almost entirely on the efforts of email marketers. The choices you make every day impact the way mailbox providers like Gmail, Outlook, and Yahoo Mail filter your emails.

“Engagement is your lifeline to reputation as a sender. It is extremely important. If you think about what mailbox providers are doing, they want their users to get the emails they want to receive... And the way they do that is by looking at engagement.”

Nick Schafer

Sr. Manager of Deliverability & Compliance, Sinch

There’s one problem. Many senders say they don’t have a strong understanding of their reputation with mailbox providers. Just 25.5% rated their knowledge of sender reputation an 8 out of 10 or higher.

There are free services available that offer insights into your sender reputation with specific providers. They include Google Postmaster Tools, Microsoft SNDS, and the Yahoo Sender Dashboard. However, even though these services don’t cost a dime, almost 70% of senders do not use them to monitor sender reputation.

You might be saying to yourself, “I’m not a postmaster. I’m a marketer. Why should I be using something like Google Postmaster Tools?”

Here’s the thing, Google Postmaster Tools and other services provide some easy-to-understand insights that are very valuable to email marketers.

Email marketing deliverability – after the open

Because high email engagement rates are correlated with better deliverability, what happens after your campaigns arrive in the inbox will have an impact on how mailbox providers choose to filter emails in the future.

This means the strategic decisions you make as an email marketer today will affect deliverability tomorrow.

That can include everything from writing engaging subject lines that improve your open rates to persuasive and creative calls-to-action that increase your click rates.

While increasing engagement metrics like opens and clicks is your goal, there are several things email marketers can do to make that happen. Here are four places to focus:

1. Mobile responsive emails: Do your campaigns look and function as expected on all devices and screen sizes? Most people primarily check their email on smartphones.

2. Email client rendering: Do you know how your email designs and code end up looking in different inboxes? Gmail, Outlook, and Apple Mail may be displaying your HTML emails differently.

3. Dark mode emails: How will your email designs look if recipients have dark mode settings turned on? Certain elements of your emails could be disappearing in the dark.

4. Email accessibility: Is it easy for everyone on your list to read and interact with what you’re sending? When some subscribers can’t read the copy or click the buttons, engagement rates will suffer.

Here’s the bottom line on the final step of email deliverability: If you expect people to engage with your campaigns, it needs to be easy and enjoyable to do so. That means sending campaigns that are optimized for mobile devices, look good in any inbox, and are accessible to as many people as possible.

Email deliverability doesn’t have to be hard

Sometimes the complexities of email deliverability may feel overwhelming. The good news is, if you take a little time to understand what it takes to reach the inbox, it won’t take long for everything to make sense.

For example, here’s a major misconception we uncovered in our Road to the inbox report:

88% of senders don’t know what the delivery rate actually measures. Many respondents think the delivery rate is an overall email deliverability metric, even more believe it measures how many emails reach the inbox. But neither are correct.

Only 12% of respondents knew that the delivery rate measures the percentage of emails sent that are accepted and delivered to any folder. That includes the spam folder. So, even if you’re getting a 98% delivery rate – that doesn’t mean 98% of your emails reached the inboxes of your subscribers.

This might be news to you, but it’s not hard to understand once you know the truth.

Want expert help with email deliverability from people who already know the truth? Sinch Mailjet Delierability Services will guide you through many of the complexities. Connect with a dedicated technical account manager (TAM) whenever you need deliverability support.