You spent hours writing copy, perfecting the design, and segmenting your list for a new email marketing campaign. But even though your email client says your emails were delivered successfully, the opens and clicks are a fraction of what you expected.
Poor email performance isn’t always because your subject line missed the mark or your timing was off. In many cases, the emails never reached your recipients’ inboxes. Gmail, Yahoo, and other providers sort messages constantly, and bulk marketing campaigns are often filtered into spam or tucked into folders people rarely check.
This is where email deliverability comes in. It’s the behind-the-scenes factor that determines whether your emails actually make it into inboxes or get pushed aside into folders no one checks. And that visibility is everything—if your recipients don’t see your emails, they can’t perform.
In this article, we’ll break down what deliverability means, walk through best practices, and share benchmarks for measuring your performance.
What is email deliverability?
At its core, email deliverability is about whether your emails actually reach inboxes where subscribers can see and interact with them. It’s different from delivery, which simply means the message was accepted by the recipient’s server, because it focuses on inbox visibility.
Think of it like receiving a package. “Delivery” is the carrier making it to your building. “Deliverability” is whether the package ends up in your personal mailbox, where you’ll notice it, or gets left in a dark corner of the mailroom, where you probably won’t.
Inbox providers use four primary signals to determine whether an email should reach a recipient’s main inbox, promotions tab, or spam folder.
Domain authentication (SPF, DKIM, DMARC)
Authentication is about proving you are who you say you are. Three common protocols make this possible:
- SPF (Sender Policy Framework): Authorizes which servers are allowed to send on behalf of your domain.
- DKIM (DomainKeys Identified Mail): Adds a digital signature so inbox providers know your message wasn’t altered in transit.
- DMARC (Domain-based Message Authentication, Reporting & Conformance): Tells inboxes how to handle suspicious messages that fail SPF or DKIM.
Without these trust signals in place, inbox providers have little reason to trust your messages.
Sender reputation
Your sender reputation works like a credit score. Inbox providers track your past behavior, including spam complaints, bounce rates, and engagement. A strong history makes it easier to reach inboxes, while a poor reputation puts your future campaigns at risk.
Subscriber engagement
Engagement shows inbox providers whether people actually value your emails. Opens, clicks, and replies are positive signals. Spam complaints, quick deletes, or consistently ignored messages are negative signals that hurt future deliverability.
Content quality
Finally, the message itself matters. Emails with misleading subject lines, image-only designs, or messy HTML raise red flags. Clear, relevant content with balanced formatting signals legitimacy and helps build trust.
Why email deliverability matters
You can write the perfect subject line, send at the right time, and design a beautiful email, but none of it matters if your message never reaches inboxes.
Deliverability is the foundation of email marketing because visibility equals opportunity: subscribers can only open, click, and convert if they actually see your messages. And when deliverability is strong, it pays off in three big ways: stronger results, stronger relationships, and stronger compliance.
Stronger results
Every email you send has indirect costs, like time spent writing copy, designing templates, and planning strategy. Deliverability determines how much return you get on that investment. If only a portion of your audience ever sees your emails, the value of all that work shrinks dramatically.
For example, a deliverability rate of 90% versus 75% on a list of 100,000 subscribers means 15,000 more people have the chance to see your email. Even with modest conversion rates, that difference can translate into hundreds—or even thousands—of additional sales.
Every improvement in deliverability increases the efficiency of your marketing efforts. When more of your emails reach inboxes, the copy you wrote, the design you polished, and the calls-to-action you crafted all work harder without any extra effort. That means higher returns without growing your list, sending more messages, or spending more on campaigns.
Stronger relationships
Deliverability also affects how subscribers perceive your brand. When your emails consistently reach inboxes and feel tailored to their needs, people recognize your messages, come to expect them, and grow more comfortable engaging with them. Over time, that reliability reinforces your credibility and helps position your brand as trustworthy.
Poor deliverability does the opposite. If your emails arrive inconsistently or not at all, subscribers may stop paying attention or unsubscribe. And if your domain isn’t properly authenticated, you risk phishing or spoofing attacks that can damage trust even further.
Strong deliverability protects the relationships you’ve worked hard to build. It ensures your brand shows up consistently, stays recognizable, and keeps subscribers confident that your messages are legitimate and worth opening.
Stronger compliance
Inbox providers and governments both set rules to protect people from spam and abuse. Failing to meet these requirements can get your emails filtered, blocked, or even expose your business to legal risk.
To stay compliant, marketers need to follow both technical and legal standards:
- Inbox provider requirements: Gmail and Yahoo now require domain authentication (SPF, DKIM, DMARC), easy one-click unsubscribes, and spam complaint rates under 0.3%.
- Legal requirements: Regulations like CAN-SPAM (U.S.), CASL (Canada), and GDPR (Europe) mandate practices such as clear sender information, consent, and functional opt-outs.
The good news is that strong deliverability practices cover most of these automatically. Authenticate your domain, send to engaged audiences, and keep complaints low, and you’ll earn inbox trust while staying compliant with evolving rules.
Six ways to improve email deliverability
Good deliverability doesn’t happen by accident. Inbox providers evaluate every message you send, looking for signs of trustworthiness, consistency, and relevance. Over time, those signals add up to determine whether your emails land in inboxes or get filtered away.
Here are six areas to focus on if you want more of your messages to reach inboxes.
1. Set up and align your domain
Authentication is the foundation of good deliverability. Without it, inbox providers have no proof you are who you say you are, and your emails are far more likely to be rejected or flagged.
Make sure you’ve set up these three protocols correctly:
- SPF authorizes which servers can send emails on your behalf.
- DKIM adds a digital signature to prove the email wasn’t altered in transit.
- DMARC ties them together, telling providers how to handle suspicious messages.
It’s also critical that the “From” address matches your sending domain. Misalignment is one of the most common reasons emails get flagged, especially under Gmail and Yahoo’s updated rules.
2. Warm up your sender reputation
If you’re sending from a new domain or have been inactive for a while, inbox providers don’t know whether to trust you. Sending large volumes right away can get you flagged as spam.
Instead, gradually warm up your domain by starting with small batches of sends and increasing volume over the first few weeks. Mix in your most engaged subscribers early, since their positive interactions (opens, clicks, replies) help establish credibility.
Some business email platforms now include automated domain warming tools that pace your sends for you, taking the guesswork out of the process. But even if you’re warming manually, the premise is the same: slow, steady growth builds a stronger reputation than sudden spikes.
3. Build and maintain an engaged list
Your list is one of the strongest factors in deliverability. Sending to people who never asked for your emails—or who stopped engaging long ago—signals to inbox providers that your messages aren’t wanted.
Focus on permission-based growth with practices like double opt-in and clear consent. Just as important, use sunset policies to regularly remove unengaged contacts after a set period. It might feel counterintuitive to shrink your list, but a smaller, healthier audience is far better for deliverability (and ROI) than a large, disengaged one.
4. Create emails that earn trust
Inbox providers don’t just check who the message is from. They also evaluate what’s inside. Subject lines, formatting, and content all factor into whether an email looks legitimate or suspicious.
Keep your messages clean and professional. That means avoiding subject lines that feel misleading, balancing text with images, and making sure your HTML is well-structured. If you need help creating on-brand emails, you can run your draft through an AI email generator to refine the copy before sending. Personalization with custom fields is also important: when messages feel relevant and tailored, people are more likely to engage, which boosts deliverability even more over time.
5. Send at the right frequency
Even great content can hurt your reputation if it’s sent too often or not often enough. Overloading inboxes leads to complaints and unsubscribes, while long gaps can make subscribers forget they signed up at all.
Find a cadence that matches your audience’s expectations. This often means segmenting your lists by engagement level or customer lifecycle so your most active subscribers hear from you more frequently, while less engaged groups receive fewer emails.
6. Monitor and adjust regularly
Deliverability isn’t static. It shifts as your reputation, audience, and sending patterns evolve, which makes regularly monitoring your email metrics essential for staying on top of things.
Check campaign-level data weekly—spam complaints, bounce rates, and engagement trends—to catch issues early. Then, take a broader view monthly by reviewing inbox placement and sender reputation in tools like Google Postmaster or your platform’s deliverability reports.
When numbers start to slip, make small adjustments to prevent bigger problems. If complaints rise, slow your sending frequency or refine your targeting. If bounces spike, clean up your list. And if inbox placement suddenly drops, re-check your authentication settings.
With these proactive steps, you can keep your program healthy for long-term email marketing success.
Benchmarks for good deliverability
So how do you know if your emails are making it to inboxes? Deliverability shows up in a few core benchmarks that can act as a health indicator for your program.
- Inbox placement rate: Average inbox placement hovers around the mid-80s, but strong senders hit 90% or higher. Dropping below that often points to issues with authentication, reputation, or list quality.
- Spam complaint rate: Gmail requires bulk senders to stay under 0.3%, though best practice is 0.1% or less—fewer than one complaint per 1,000 emails. High complaint rates usually point to problems with relevance, frequency, or subject lines that feel misleading.
- Bounce rate: Healthy lists stay under 2% bounces. Rates above 5% usually indicate stale or low-quality data and can damage your reputation. Most high bounce rates come from poor list-building practices like buying lists or failing to clean lists regularly.
- Engagement: With open rates less reliable due to Apple’s Mail Privacy Protection, focus on clicks, replies, and unsubscribes as stronger indicators. Low engagement often points to problems with targeting, content relevance, or sending too frequently, while steady interaction tells inbox providers your messages are wanted.
Together, these benchmarks give you a snapshot of deliverability health. Meeting them means your campaigns are reaching subscribers and earning attention. Missing them means it’s time to troubleshoot your process before damage compounds.
Email marketing deliverability keeps your emails on the right track
Email marketing doesn’t stop at hitting “send.” What truly determines success is whether those messages arrive where subscribers will see them, and whether you’ve built the trust to keep them coming back for more. Deliverability is the filter that decides which brands get heard and which get lost along the way.
Fortunately, deliverability isn’t all luck or guesswork. With the right foundation in place—authenticated domains, a healthy list, thoughtful sending habits, and ongoing monitoring—you can consistently earn your spot in the inbox. That way, the time and effort you put into creating campaigns pays off with real engagement.
Looking for tools to make high deliverability easier to achieve? Check out Heymarket’s omnichannel shared inbox.
