Email Deliverability 101 for Email Marketers

May 26, 2022
Written by
Nathalia Velez Ryan
Opinions expressed by Twilio contributors are their own
Reviewed by
Ayanna Julien
Opinions expressed by Twilio contributors are their own

Email Deliverability 101 for Email Marketers

In email marketing, crafting compelling emails and sending them to optimized segments is only half of the equation. And all that work is in vain if those emails don’t make it to your recipients’ inboxes.

Email deliverability is the other half, ensuring that your emails reach recipients and don’t end up in the spam folder. However, multiple factors impact deliverability, many of which have to do with your sender reputation—or inbox service providers’ (ISPs) impression of you as a sender. 

In this post, we’ll explain what email deliverability is, why it’s important, and the factors that impact it. 

What is email deliverability?

Email deliverability is the ability to get emails delivered to your recipients’ inboxes. Sounds simple, right? But it’s not just about subscribing users to your email list and hitting Send on your campaigns. There are factors behind the scenes that determine where your emails end up. 

ISPs consider various factors when deciding where to place an email, focusing on the sender’s internet protocol (IP) reputation, domain familiarity, and adherence to sender best practices. Additionally, ISPs pay attention to what recipients have to say. If enough people mark an email sender as spam, this signals to ISPs the need to protect recipients from this sender. 

So how does deliverability differ from email delivery? Let’s explore this question next. 

What's the difference between deliverability and delivery?

Having a healthy delivery rate doesn’t necessarily mean that you don’t have deliverability issues. These are actually 2 different metrics, although one influences the other. 
  • Email delivery refers to the email successfully reaching the recipient, meaning the email didn’t bounce due to an inactive email address or another reason. A high bounce rate can affect your sender reputation and ultimately your deliverability. But email list maintenance, which we’ll cover below, is the main factor that impacts delivery.
  • Email deliverability refers to where the email lands once it reaches the recipient, e.g., the inbox or spam folder. Factors that affect deliverability include sender and domain reputation, spam complaints, and email authentication. We’ll go more in depth on these topics below. 

Why is email deliverability important?

Here are a few reasons why good email deliverability is crucial to the success of your email program. It helps you:

Reach the inbox 

As we’ve already established, improving email deliverability is all about ensuring the emails you work so hard on end up in recipients’ inboxes, not in the spam folder or blocked altogether. If someone signed up for your email list, you want to deliver on your promise and make sure they receive your emails. 

Think of it this way: say a recipient subscribes to your email list and a competitor’s. Your email lands in the spam folder while the competition makes it to the recipient's inbox. That means the competitor gets the opportunity to engage the user while you get to languish in spam-land. 

Maintain a good sender reputation

The last thing you want is for ISPs or recipients to perceive you as a spammer. If certain signals—which we’ll discuss below—begin to negatively impact your sender reputation, your deliverability will suffer, which, in turn, will hurt your reputation. This is a cycle you don’t want to get stuck in.

Achieve your marketing goals 

Your email campaigns have an ultimate goal—e.g., purchases, downloads, sign-ups, etc.—and you can’t reach that goal if subscribers don’t get your emails. If your email deliverability is poor, you won’t see the conversions you’re seeking. 

What affects email deliverability?

While the content and email design have some impact on deliverability because of the ability to distinguish legitimate emails from spam, these 2 aren’t the only factors involved. Deliverability is largely related to behind-the-scenes aspects of your email program tied to your sender reputation and list management. 

According to Twilio SendGrid’s Deliverability experts, the following are some of the top factors that can influence deliverability, along with tips on how to address them.

Email list maintenance 

Regularly cleaning up your email list will help you reduce hard bounces and unopened emails, which ISPs monitor. Here are a few ways to keep your email list clean. 

Address unengaged recipients 

Have a segment of recipients who ignore or delete your emails? Consider these tactics: 
  • Try a reengagement campaign to give these users a chance to tell you how often they want to hear from you or unsubscribe if they’re no longer interested in your communications.
  • Reduce the frequency with which you email these users. 
  • Sunset any old email addresses that didn’t reply to your reengagement campaign and continue to ignore your emails. 
(P.S. If you're looking for further insight into your email lists and audiences beyond email, explore how Twilio Segment can help you harness customer data and personalize communications.)

Clean up invalid addresses 

Hard bounces typically come from invalid email addresses (such as a company email address for someone no longer employed there) or incorrectly entered email addresses. 

No matter where these invalid email addresses come from, you should regularly remove them to avoid hard bounces, which you want to keep under 0.5%. This signals to ISPs that you’re intentionally sending emails to valid addresses and not engaging in any potentially spammy tactics. 

Use an email validation tool

An email validation tool helps ensure you only add valid email addresses to your list. Twilio SendGrid’s Email Address Validation API, for example, can identify false entries, such as mistyped, inactive, or nonexistent email addresses. Implementing email validation when users sign up for your list can help cut down on hard bounces. 

Spam complaints 

One of the quickest ways to end up in the spam folder, or worse, a blocklist, is to have multiple recipients flag you as spam. But don’t worry. There are a few ways to reduce spam complaints. 

Implement double opt-in 

When users subscribe to your email list, use a double opt-in method to ensure that they want to receive your emails. 

The double opt-in process typically looks like this: 
  1. The user signs up for your email list by entering their information on a sign-up form. 
  2. You send the user an automated email welcoming them to your email list and asking them to confirm that they want to subscribe. 
  3. The user clicks on the call to action to confirm their subscription. 
With this opt-in process, you can feel more confident that the user is unlikely to mark your emails as spam. Plus, it confirms they entered their email address correctly. 

Honor unsubscribes right away 

One of the golden rules of email marketing is you unsubscribe users from your list as soon as they ask you to do so. Otherwise, you could risk them marking your emails as spam. Read up on email unsubscribe best practices

Email authentication 

There are a few authentication protocols senders use to show ISPs they are legitimate senders and not spammers or spoofers. Failing to authenticate through these protocols can ultimately hurt your deliverability. 

These protocols include: 

Sender reputation 

Your sender reputation helps ISPs determine whether you’re a legitimate sender and where to place your emails. The way subscribers interact with your emails, whether engaging with the content or marking them as spam, influences your sender reputation.

There are 2 different types: IP reputation and domain reputation. Plus, you can use a few different tools to check your current sender reputation. Once you know your score, follow best practices to protect or improve it. 

Send strong emails with Twilio SendGrid

Now that you understand which factors impact this metric, check out our article 8 Best Practices to Improve Your Email Deliverability

Email deliverability doesn’t have to be a mystery. Twilio SendGrid’s new Deliverability Insights dashboard harnesses data to give you actionable insights to improve your deliverability. 

Learn more about how Twilio SendGrid helps deliver your emails

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