One fact that took me longer than I’d like to admit to discover is that email deliverability isn’t some mysterious black box controlled by tech wizards. But rather a completely logical system that rewards good email practices and penalizes bad ones. Sounds like karma, huh?
If you’re sending emails to market your business (and who isn’t these days?), listen up.
Email deliverability helps email marketers gauge whether or not their wonderfully designed email templates are reaching their subscribers’ inboxes.
Good email deliverability means your emails land in the primary inbox. Poor deliverability, on the other hand, means that most of the delivered emails don’t make it to the primary inbox but get tossed into the spam folder.
48% of senders finding it challenging to stay out of the spam folder says a lot about how important deliverability is to your brand’s email marketing success.
But you know what’s making email deliverability even more important? Google and Yahoo!
Yes, these major ESPs (Email Service Providers) rolled out new bulk email sender requirements in 2024. They set their threshold for the spam complaint rate to 0.3%.
Once your spam complaint rate exceeds 0.1%, you’re officially in the “danger zone”. Hit 0.3%, and you’re basically asking to get blocklisted. And your email deliverability takes the brunt of it.
If you’re an email marketer already following deliverability best practices, you can exhale. Because you are protecting your subscribers from intrusive, spammy emails.
If not? Well, as Kate Nowrouzi, VP of Deliverability at Sinch, puts it, prioritizing email deliverability is “the only way if you want email to remain an effective channel.”
So, what core factors should you focus on for strong email deliverability? Let’s find out.
What Is Email Deliverability?
This Email Mavlers’ latest infographic on Email Trends In 2025 predicts email deliverability to be the critical focus for marketers this year and ahead. So, what exactly is this email deliverability that industry experts can’t stop raving about?
Email deliverability is the ability to deliver emails such that they reach subscribers’s inboxes and avoid landing in spam folders.
This is important because email campaigns that end up in a spam folder have a higher risk of being overlooked or even deleted. They suffer miserable open rates. No amount of perfectly designed email templates can save your email campaign from getting wasted, as you don’t get your audience to read them.
But it never stops at a single email campaign. It throws your email campaigns into the downward spiral of more emails getting marked as spam due to the lack of email engagement.
So, what’s a good email deliverability rate?
In an ideal world? 100%. In reality, Carin Slater, Manager of Lifecycle Email Marketing at Litmus, says they aim for inbox placement above 90%. And if it drops below 90%, they immediately investigate what’s happening.
Many factors determine your email deliverability rate. Some you can control. Some are beyond the sender’s direct control—server issues, full inbox, etc. Let’s not worry about what we can’t control and focus on what we can to improve email deliverability.
Top 6 Factors To Consider That Influence Email Deliverability
- Sender Reputation
Your ESP gives you a sender reputation score to decide whether the emails you send to your subscribers are inbox-worthy or should end up in spam folders. A higher sender reputation score means higher trust from your ESP. Higher trust means better inbox placement.
Translation: Having a good sender reputation in the eyes of ESPs is important for high email deliverability rates.
Every ESP has its own way of compiling multiple factors into a unique sender reputation score. But that’s a whole new can of worms to be opened some other day.
For now, remember that the subscribers’ behavior with your emails, opens, clicks, etc, signals ESPs that you’re a legit and inbox-worthy sender.
2. Inbox Placement
Inbox placement is the particular folder your emails appear after getting delivered to subscribers—primary inbox, promotions, newsletters, social or spam folder. Ending up in folders other than the primary inbox means your recipients may not see them as often.
You want to ensure good email engagement to have inbox placement. When an engaged audience regularly opens, clicks, and interacts with your emails, ESPs take notice. It’s a sign that your emails are valuable. This, in turn, helps you to avert email deliverability issues.
3. Email Authentication
Email authentication protocols are critical to email deliverability. Setting up proper authentication protocols verifies your emails as legitimate, reducing the chance of being flagged as spam.
Andrew King, Founder of Email Love, stresses that bulk senders must authenticate emails using SPF, DKIM, and DMARC. Yes, those are alphabet soup acronyms, but your email service should help you set them up. This will help achieve inbox placement with ESPs.
Apart from supporting a good sender reputation, authentication protects you and your customers from phishing emails.
4. Email List Hygiene
Building and maintaining a high-quality email list is more important than you might think when it comes to email deliverability. Because the health of your list contributes to the way your contacts engage with your emails. And that says a lot about what kind of sender you are.
Having a list full of uninterested, inactive, or invalid email addresses is like inviting the email delivery gods to smite you. In the end, you will only hurt your chances of reaching those who actually do want to receive your emails. How, you ask?
Neglecting regular list cleaning causes you to fall into the spam traps of problematic email contacts. Continue sending emails to those profiles who never engage—or worse, mark your emails as spam and be ready to see your sender reputation sink faster than the Titanic.
Said another way, maintaining a clean list of loyal and engaged subscribers will help you stay out of the spam folders and improve deliverability rates.
5. Email Volume and Send Frequency
Email volume and frequency is pivotal to deliverability. ESPs use them as a reference to assess whether an email sender is up to spammy practices. A sudden spike in email volume looks pretty sus to spam filters. And might as well alert them to the possible spam virus. This could get you blocked.
6. Email Content
ESPs use spam filters to gauge whether your emails reach the inbox based on email content. These filters scan everything—your subject line, content, images, and links.
If your content feels irrelevant, spammy, or just plain unwanted to the recipient, it could be flagged as spam. And each time that happens? Your sender reputation takes a hit, making it even harder for future emails to land in the inbox.
Wrapping Up
Strong email deliverability’s biggest benefits are better inbox placement, improved customer satisfaction, increased revenue, and higher engagement metrics. It’s simple math: emails that don’t reach inboxes can’t drive sales.
The factors mentioned above influence an email’s likelihood of being successfully delivered. Building sender reputation, maintaining clean, engaged email lists, creating relevant content, and setting up authentication help you better your odds of meeting your audience in their inbox.
And isn’t that the whole point of email marketing in the first place?