Looking to improve your email deliverability? You've come to the right place. We eat, sleep, and breathe email deliverability at Twilio SendGrid, and we realize it's arguably the most important metric for your email program.
Why?
Because your emails can't be opened or clicked unless they get delivered first. Deliverability rates impact everything.
Fortunately, email deliverability isn't rocket science. You just need to follow email deliverability best practices, get your ducks in a row, and be a good sender—and voila—your email deliverability will improve.
Below, we'll walk you through everything you need to know to improve email deliverability and send your email program to new heights.
Email deliverability refers to the ability of your emails to successfully reach recipients' inboxes. It's not just about whether an email gets sent—it's about whether it lands where it's supposed to.
Deliverability is typically measured as a rate: the percentage of your emails that make it to inboxes out of the total number of emails you send.
Here's a breakdown of key components:
Delivery: When an email is accepted by the recipient's mail server
Deliverability: When an email actually reaches the inbox (not spam or junk folders)
Delivery rate: The percentage of emails accepted by recipient servers
Deliverability rate: The percentage of emails that land in inboxes
Pretty straightforward, right?
Improving your email deliverability isn't just about technical fixes—it's about creating a holistic strategy that prioritizes subscriber engagement and sender reputation. By focusing on deliverability, you're setting the foundation for a successful email marketing program that drives real results for your business.
So, how do you make sure your email gets delivered? Luckily there are proven techniques to prevent failures and improve your email delivery rates for the long term. This guide offers an overview of the steps most businesses need to take to maximize their email deliverability:
Impersonation is not a form of flattery in the email world–it’s one of the quickest ways to tank your sender reputation. If you are not enabling Sender Policy Framework (SPF) and Domain Keys Identified Mail (DKIM), you risk falling victim to email spoofing (somebody taking control of your email domain) and, as a result, experiencing poor delivery rates.
Authenticating your email with SPF and DKIM proves to the ISPs that you really are who you say you are and are worthy to send email. Email authentication can be tricky, so it deserves its own post. Read up on email authentication in our 101 post, so you know that you are covered.
As your email program continues to grow, it’s important to keep in mind that you will need the proper email infrastructure as you scale. Once you reach 25,000 daily emails, you will want to send on a dedicated IP address. And when you add a dedicated IP address, you’ll have to properly warm it up before sending to your entire list so that your gain trust with the ISPs that you are sending wanted email.
Don’t just keep adding IPs to avoid penalties. ISPs are smarter than that and they will end up blocking an entire IP pool if they suspect this is what you’re doing.
How you collect email addresses plays a large role in your deliverability rates. An optimized opt-in process ensures that your email list is full of engaged users. If you are sending email to people who weren’t aware or didn’t agree to receive messages from you, they will mark your emails as spam and the ISPs will think you’re spamming everyone on your list (even those on your email list that want to receive your email!).
We recommend using double opt-in which involves two verifications for the user and proves far more successful in cultivating an engaged email list. Check out our How To Grow Your Email List Guide to learn more about growing your email list the right way.
Your subject lines are crucial pieces of content that will ultimately determine if a user opens your emails. Although ISPs continue to become more sophisticated in their filtering systems and certain catchphrases won’t necessarily place you in the spam folder automatically, it’s wise to avoid using common spam phrases in general.
Some of these phrases include:
Eliminate your debt
Risk-free
FREE!!!
There is no absolute rule or words that, if avoided, will guarantee you a place in the inbox. And many legitimate emails might include the words above. But when you’re writing your subject lines, focus on the genuine value of the message without sounding pushy or salesy.
Once your recipients have agreed to receive email from you, provide a preference center so that they can decide just how frequently they want to receive email from your brand. Doing so helps put your recipients in control and helps keep them happy. This happiness generally translates to better engagement (which is noticed by the ISPs).
Don’t let your ego get in the way of your email deliverability. The longer you keep inactive and unengaged users on your email list, the more you risk damage to your reputation and deliverability rates.
Providing a clear and easy way for your users to unsubscribe from your emails helps automate the process, but it’s also important to scrub your list on a regular basis so that your email list is healthy and only includes people who engage with your emails.
Spam traps are email addresses set in place by ISPs and email community organizations to catch spammers “in the act” from sending unwanted email. If a sender ends up sending to a spam trap, it is immediately flagged and put on a deny list.
It’s extremely challenging to get yourself off a deny list, so it’s best to never end up on one in the first place. Email marketers can avoid spam traps by keeping a clean list of engaged users and to never, ever, purchase an email list of any sort.
You have to please two parties when trying to improve your email deliverability—the ISPs and your recipients. But if you please the latter, the former will already be taken care of. ISPs protect the end-user and if they indicate they are happy, then the ISPs will be pleased with your sending and keep placing your email in the inbox.
Above all, if your recipients enjoy and derive value from your email, they will interact with your messages.
A sunset policy is a strategic approach to managing inactive subscribers, which can significantly impact your email deliverability. Regularly removing unengaged subscribers keeps your list healthy and responsive. ISPs view consistent sending to inactive addresses as a red flag, which can harm your reputation.
Plus, by focusing on active subscribers, your overall engagement metrics will likely improve.
How to implement a sunset policy:
Define inactivity: Determine what constitutes an inactive subscriber for your business (e.g., no opens or clicks in 6 months).
Create a re-engagement campaign: Before removing inactive subscribers, try to win them back with a targeted campaign.
Set up an automated process: Use email automation to tag and manage inactive subscribers over time.
Remove with care: If re-engagement fails, remove inactive subscribers from your main list—but consider keeping them in a separate suppression list.
Remember, a smaller, more engaged list is far more valuable than a large list of unresponsive subscribers.
Let's look at some real-world examples of companies that successfully boosted their email deliverability using SendGrid's solutions and best practices:
Glassdoor, the popular job search and company review platform, faced the challenge of scaling its email program while maintaining high deliverability rates.
Challenge: Maintaining high deliverability rates while sending millions of emails daily across multiple IPs and domains.
Solution: Implemented SendGrid's Email API and leveraged dedicated IP addresses. They also partnered with SendGrid's Expert Services team for strategic guidance.
Results:
99.5% average monthly delivery rate
0.007% average monthly spam rate
30% unique email open rates for high-volume emails
"Deliverability is more of an art than a science—the landscape is constantly changing," explained Nonso Maduka, Director of Product Management at Glassdoor. "We're a lot more confident knowing we have someone in our corner at the leading edge of what's happening in the deliverability space."
Shopify, a global commerce company, needed to provide its 1.7 million merchants with reliable email tools for both transactional and marketing communications.
Challenge: Scaling email infrastructure to support both transactional notifications and email marketing for a vast number of merchants.
Solution: Utilized SendGrid's Email API, implemented DKIM signing, and leveraged SendGrid's IP pool management and Expert Services.
Results:
99.5% overall delivered rate
91.3% inbox placement rate
Less than 4 sec p90 average delivery time on all transactional emails
"SendGrid streamlines our processes with its custom mailbox relay, deliverability optimization with automated retries in response to mailbox error codes, and connection management," said Sébastien Lavoie, Shopify's Notification Platform Development Manager.
Klaviyo, a marketing platform for online businesses, needed a scalable email solution to support its growing customer base.
Challenge: Finding a reliable, scalable email delivery solution that would allow them to focus on building experiences for customers.
Solution: Built their email platform upon SendGrid's Email API, leveraging its delivery expertise and infrastructure.
Results:
99.94% average delivery rate
46.94% open rates for automated welcome series emails
Ability to send around 10 billion emails per month
Median delivery speed of 1.9 seconds
"Using digital communications is critical to engaging customers and building a business online. Working with Twilio SendGrid has allowed Klaviyo to focus on building innovative solutions and not worry about email delivery," said Hongbin Yin, Engineering Manager of Klaviyo's Email Team.
Yes, open rates, click rates, design elements, and calls-to-action (CTAs) matter, too—but they should all be secondary to improving your email deliverability.
