What is Email Deliverability and How Can You Improve It?

• Email deliverability defined: It’s your ability to land messages in subscriber inboxes rather than spam or junk folders.
• Why it matters: If your messages don’t reach inboxes, recipients can’t open them, click your links, or take action.
• Delivery vs. deliverability: Delivery means the recipient’s server accepted your email, while deliverability measures whether it actually landed in the inbox or gets diverted to spam. 
• How you improve it: Set up authentication protocols, keep your list clean and segmented, personalize content, optimize for mobile, and monitor engagement signals.

Email deliverability determines whether your messages reach the inbox instead of bouncing, getting blocked, or ending up in spam. Why is it so critical to your email marketing success? Simply put: opens, clicks, and conversions can only happen after your email reaches its intended destination. If a receiving mailbox rejects it, or if spam filters bury it, subscribers will never see the email content you worked so hard to craft.

In this blog, we’ll go through what email deliverability is and how it differs from email delivery. You’ll also learn what qualifies as a good deliverability rate, how to track performance, plus the steps and tools you need to get more emails where they belong.

What is email deliverability?

Email deliverability, also called inbox placement, indicates how many of your messages land in recipient inboxes rather than spam or junk folders. For Gmail, landing in the Promotions or Updates tab is still considered successful deliverability for marketing emails. Getting your emails in the right tab helps people find your content where they expect to see similar messages.

A high deliverability rate means your emails reach your audience so they can open and read your content. On the flip side, poor deliverability signals that something in your message or sending practices triggered spam filters.

Email delivery vs. email deliverability

Email delivery and email deliverability get mixed up often. While they’re both important, email deliverability goes one step further. 

Let’s compare them side by side to understand exactly what they do:

Let’s say you send a weekly newsletter through your email marketing platform. If Gmail accepts it and places it in Promotions, that still counts as successful deliverability because subscribers can see and act on the message. But if Gmail accepts the email only to dump it into spam, delivery was completed, but deliverability failed.

Why should you monitor email deliverability?

Think of deliverability as the bridge between the resources you put into your campaigns and return on investment (ROI). Low placement means fewer eyes on your message, which drags down opens, clicks, and sales. When you hit the inbox, though, you can turn subscribers into paying customers who drive direct revenue.

Here’s why email deliverability matters:

• Protecting sending reputation: If recipients regularly open and click your emails, internet service providers (like Gmail or Yahoo) view your domain as trustworthy. That positive feedback loop safeguards you against sudden blocklisting. 
• Boosting customer retention: Subscribers count on timely email updates, whether these are transactional emails like password resets and order confirmations or loyalty campaigns like milestone or anniversary messages. Consistent delivery reinforces trust and gives customers reasons to stick around. 
• Maintaining list hygiene: Tracking deliverability helps you flag hard bounces instantly and remove them to keep list engagement metrics high. Sending to invalid or inactive subscribers also increases email marketing costs since most platforms use contact-based pricing.
• Detecting technical issues early: Authentication issues or server errors can send your emails to spam without prior notification. By keeping an eye on your deliverability rate, it’s easier to catch misconfigurations before email clients penalize your sender domain.

What is a good email deliverability rate?

According to Validity’s 2025 Email Deliverability Benchmark Report, the average global inbox placement rate in 2024 was 83.5%. They also found that 6.7% of emails landed in spam and 9.8% were blocked or deferred. This means about one in six marketing emails never reaches the inbox. 

Deliverability also varies between marketing and transactional emails. Transactional emails are triggered by customer behavior, such as purchasing a product or requesting a password reset. Because recipients usually expect these timely messages, mailbox filters treat them more favorably than bulk promotional sends.

Marketing emails, on the other hand, encourage subscribers to take some kind of action or make a purchase through persuasive copy and a call-to-action. Since they’re typically mass email sends, they face stricter scrutiny from spam filters than individual transactional emails.

So, what should you be aiming for? Benchmarks aside, work toward low bounce rates and strong inbox placement. Most healthy senders aim to reach 90% placement or higher and continue optimizing from there.

Metrics and tools to monitor and test email deliverability

The most straightforward way to track email deliverability is by monitoring your core performance metrics. 

Pay close attention to:

• Open rate
• Click-through rate
• Unsubscribe rate
• Spam rate

A sudden drop in opens and click-throughs often is an early warning sign that your emails aren’t reaching subscribers. At the same time, a rise in unsubscribes or spam complaints usually points to list or content quality issues. 

Most email solutions offer built-in reporting tools to track these numbers. Beyond standard email analytics, platforms like Constant Contact let you preview how your email renders on different devices and send test emails to multiple addresses across different mailbox providers. 

Besides your primary email marketing service, you can use standalone tools to see if your domain is on a blocklist before sending: 

• Sender Score: Checks your domain reputation to show how inbox providers view your sending domain.
• MXToolbox: Identifies DNS issues and checks whether your domain appears on major blocklists.
• Mail Tester: Helps you run pre-send checks to evaluate your content against common spam triggers, such as clickbait copy or ALL-CAPS text.

First steps: Setting up your deliverability foundation

Before optimizing your campaign content or sending schedules, you need a strong foundation that’s essential for building trust with mailbox providers.

1. Understand and protect your sender reputation

Like reputations in real life, it takes time to repair damage in email marketing. Who decides your email sender reputation? Major inbox providers like Gmail, Yahoo, and Outlook assign trust scores to your domain and sending IP address based on specific subscriber behaviors.

These are divided into positive and negative signals:

• Positive signals: High open and click rates, as well as recipients moving your emails out of the spam folder, adding your address to their contact list, and replying to your messages.
• Negative signals: High spam complaint and unsubscribe rates, increased bounce rates (sending to non-existent addresses), unsubscriptions, and hits on spam traps. 

That’s why it’s always better to be proactive. Start by registering your domain with Google Postmaster Tools and Microsoft SNDS (Smart Network Data Services) to track your reputation and IP health scores. 

Keep in mind that Google and Yahoo enforce strict penalties if complaints reach 0.3%, so try to keep your complaint rate under 0.1%. Low bounce rates are equally critical for domain health. Removing invalid email addresses prevents algorithms from flagging your domain. 

2. Choose a reliable email service provider

If you’re new to email marketing, you may think it’s enough to use Gmail or Microsoft Outlook as a professional email service provider (ESP). However, Gmail and Outlook are mostly designed for personal communication, not bulk promotional and transactional emails. 

Spam filters are suspicious about brands that use these email clients to send blast marketing emails. So, unless you switch to a reliable ESP, your emails could end up in spam.

A dedicated email platform provides the necessary infrastructure to send high-volume campaigns and monitor key metrics. Most of them also offer setup guidance for authentication along with tools to build and maintain healthy, compliant email lists. 

Constant Contact, for instance, has a 98% inbox rate based on Validity Everest 2025 inbox test results, so using it as your email marketing platform can help you get your emails delivered. But you still need to hold up your end of the bargain, for example by segmenting your list and sending personalized emails that don’t feel spammy.

3. Set up email authentication

Google, Microsoft, and Yahoo set certain authentication standards for high-volume senders, such as configuring SPF and DKIM and publishing a DMARC policy. Because these requirements are standard across major providers, authenticating your domain should be a top priority. 

It’s best practice to use your own business sending domain, which you can set up through web hosts like Bluehost, GoDaddy, or HostGator. 

Once your domain is set up, configure these protocols to authenticate your domain:

• SPF (Sender Policy Framework): An SPF record publishes an authorized list of server IP addresses permitted to send emails on behalf of your domain. 
• DKIM (DomainKeys Identified Mail): Adds a cryptographic digital signature to your messages, confirming they weren’t altered in transit and really originated from your domain.
• DMARC (Domain-based Message Authentication, Reporting, and Conformance): Tells receiving mail servers how to handle messages that fail SPF or DKIM checks. The options include no action (meaning the message gets delivered), sending suspicious emails to quarantine, or blocking them entirely. 

It may sound too technical, but your ESP’s step-by-step guides or an IT professional can help save you headaches down the line. Ultimately, sending from your own fully authenticated domain builds strong reputation and protects your brand credibility. 

Take a look at this example of an obvious spam email with an unauthenticated, suspicious sender address:

4. Get consent with double opt-in

Using double opt-in for new signups is a reliable way to ensure recipients actually want your emails. With this process, you send an automated email asking new subscribers to confirm their address by clicking a CTA button. 

Like this:

This extra step might sound counterproductive when tactics like purchasing email lists seem to offer a shortcut. Minimum effort, quicker results, right? 

But the truth is you have zero control over their quality. And quality is more important than quantity when building an email list. People who haven’t opted in are rarely interested in your offers. So, they won’t hesitate to mark your emails as spam or even report your domain. On top of that, buying lists violates the policies of any reputable ESP and risks severe legal penalties under regulations like GDPR and CAN-SPAM Act. 

Best practices to improve email deliverability

Now that you know how to start email sending on the right foot, let’s go through the key do’s and don’ts that will help you improve deliverability over time.

Do: Segment your email list

One of the most common email marketing mistakes is dumping every email address you have into a single list and then blasting campaigns to everyone. Your subscribers have different needs and interests. So, the more generic an email feels, the more likely they are to mark it as spam.

List segmentation involves breaking up your email list into smaller, targeted groups, ensuring you send the most relevant messages to the right people. You can group your audience by demographics, preferences, and location to deliver tailored promotions and resources. 

How you organize your list depends on your business, products, and target audience. First, use the data you already have, such as information gathered during signup or the subscriber’s browsing and buying history.

To get even more accurate data, go straight to the source, encouraging subscribers to update their email preferences or take short surveys on your site and social channels.

Don’t: Ignore list hygiene

An email list built with double opt-in and segmentation is a great start, but keeping it clean is an ongoing effort. Rather than requiring you to parse complex technical error messages, modern email platforms analyze bounce feedback automatically, sorting delivery failures into straightforward categories like “non-existent address” or “undeliverable.”

Additionally, tools like a bulk email verifier can help you proactively identify delivery failures for a cleaner list.

The bottom line is simple: any address that bounces multiple times should be removed or moved to a suppression list. Continuing to send messages to invalid or repeatedly bouncing addresses damages your domain reputation and drives up your platform costs.

Finally, deal with dormant subscribers by sending targeted re-engagement campaigns to see whether they still want to hear from you. If they remain inactive after a few attempts, remove them. Sending to people who ignore your messages ultimately hurts your deliverability.

Do: Avoid spammy or low-value content

You know what leads people to mark an email as spam? A message with zero value. When people sign up for your list, they expect useful content and offers that solve their problems. To meet their expectations, focus on educating and entertaining your target audience rather than just selling.

Trying to get noticed with all-caps words like FREE or CLICK HERE might sound harmless. But spam filters scan for formatting patterns that match known spam.

To pass filters and keep deliverability high, avoid these common traps in your subject lines and body copy:

• Overusing sales-heavy language, too aggressive pitches, and exaggerated claims
• Stuffing links, especially if they’re unrelated to your primary call-to-action
• Including excessive punctuation or writing entire sentences in ALL CAPS
• Adding words associated with spam, such as “guaranteed” or “act now”
• Writing misleading subject lines that don’t match the content inside the email

Lastly, make sure your recipients can reply to you. One of email marketing’s biggest strengths is initiating conversations. A “no reply” email address does the exact opposite, not to mention it’s a popular tactic among spammers.

Do: Create personalized content

Once you’ve got a more focused email list, creating meaningful content for your target audience gets easier. The key word here is relevance. The person behind the inbox should receive an engaging, relatable email every single time. This kind of personalization makes it less likely they’ll unsubscribe or mark your message as spam.

You can start with an automated welcome series triggered when a new subscriber signs up or completes their first purchase. Keep recipient demographics, habits, and preferences at the forefront to craft an email sequence that shares your brand’s story and values.

Personalization isn’t limited to what you send but also extends to who sends the message. Meaning your email should always come from a recognizable sender name. If your business is “Joe’s Wine Cellar,” use that or “Joe from Joe’s Wine Cellar” instead of just “Joe Smith,” which most recipients won’t recognize.

Do: Optimize designs for mobile and consistency

According to ZeroBounce’s Email Statistics Report, 64% of respondents check emails on mobile devices. Using a mobile-friendly email design ensures that this large percentage of your audience enjoys the same no-frustration experience as desktop users.

Let’s see what an email campaign optimized for mobile looks like:

• Single-column layout that keeps things simple and focused
• Clean design with ample white space and structured sections
• A single or a few CTAs that clearly communicate what happens next
• A few visuals (1-3 is ideal) with alt text to follow accessibility standards
• Readable font sizes, at least 14 pt for body text, and easily tappable buttons
• High color contrast to ensure your message stands out
• Short, concise copy that conveys the email’s purpose right away 

Effective email design also means staying true to your brand identity. Each email should have a consistent look and feel, including the visual cues that set your business apart from the competition. Place your logo prominently and use the same color palette and fonts for each email to create a cohesive image that makes your campaigns instantly recognizable.

Email marketing platforms like Constant Contact offer pre-made, responsive email templates to ensure your messages look as intended on all screens. Constant Contact also lets you create your own Brand Kit so your unique assets are ready to use in every campaign.

Don’t: Hide your unsubscribe link 

If recipients want out, make it easy for them. You might think “the more, the merrier,” but that’s not the case with email lists. People who choose to unsubscribe have likely lost interest in your products or services. Keeping these contacts only drags down your engagement metrics since they won’t open or click your emails anyway.

Place a prominent and clear unsubscribe link in your footer. This means not using tiny fonts or low-contrast colors to hide the option. 

Making it difficult for people to leave leads to distrust and spam complaints. On top of that, hiding your unsubscribe link is a clear violation of the CAN-SPAM Act which aims to protect subscribers from spam and phishing attempts.

Also, when people click on unsubscribe, don’t force them through a multi-step process. While you can include a brief survey asking why they’re leaving, keep responding optional so you don’t add unnecessary friction.

Do: Send with a schedule

Brands that suddenly send a large volume of emails every day are likely to get flagged as spam by inbox providers. This is especially true if you’re just starting out on a new domain or IP address. That’s because spam filters expect reputable senders to warm up their domain. Simply put, you start with a low sending volume and gradually increase it as you build up your IP and domain reputation.

Then, maintain a regular sending frequency that serves your objectives and readers alike. Not only will this consistent schedule help boost email deliverability, but it will also build trust with your customers.

To take it a step further, consider using a preference center on your sign-up forms or in your email footer. That way, subscribers can easily choose their preferred sending frequency and specific topics they want to learn about.

It’s also wise to think ahead to busy seasons (like holidays or sales) and ramp up your email volume gradually in advance. Creating and following a marketing calendar keeps your campaigns organized.

Want an in-depth playbook for reaching subscriber inboxes? You can download Constant Contact’s Strategies for Inbox Success guide to maximize your chances of getting your emails delivered.

Overcome email deliverability challenges 

Staying on top of email deliverability can feel overwhelming, but you don’t have to navigate domain authentication, spam filters, and list maintenance alone. Constant Contact handles the heavy technical lifting so you can focus on building meaningful relationships with your audience.

With guided authentication setup for SPF, DKIM, and DMARC, simplified bounce reporting that automatically parses delivery failures into clear categories, and pre-send device previewing tools, Constant Contact turns deliverability best practices into effortless, automated habits. Real-time engagement analytics give you complete visibility over your sender reputation and list health, helping back up an industry-leading 98% inbox placement rate.

Ready to simplify your sending strategy and reach more subscriber inboxes? Start your free 30-day trial of Constant Contact today and put your email deliverability on autopilot.

FAQs

1. What is a good email deliverability rate?

A successful email marketing program results in low bounces, close to zero spam complaints, and high inbox placement. Aim for a placement rate of at least 90%, compared to the local average of 83.5% that Validity’s 2025 Email Deliverability Benchmark Report shows. Even if you’re above average, there’s always room for improvement through domain authentication, list hygiene, segmentation, and ongoing subscriber engagement.

2. How do SPF, DKIM, and DMARC affect deliverability?

Without proper authentication, major mailbox providers may flag or reject messages from unverified domains. Google, Yahoo, and Microsoft enforce mandatory SPF, DKIM, and DMARC alignment for bulk senders to prevent domain spoofing and unauthorized sending. When paired with a spam complaint rate below 0.1%, proper authentication increases your chances of landing in the primary inbox. 

3. When should you use a dedicated IP address?

A shared IP is ideal if you send fewer than 300,000 emails per month. In this case, using a reliable ESP with a managed pool of shared IPs works best. Switching to a dedicated IP makes sense once you reach higher sending volumes and need full control over your IP reputation so other senders’ bad habits don’t impact your deliverability. Keep in mind that shared IPs are usually included in standard ESP plans, whereas dedicated IPs carry an additional fee.

4. What should you do to recover if your domain gets blocklisted? 

If your domain is listed on a major blocklist like Spamhaus or Barracuda, immediately pause sending and identify the cause, such as broken authentication or a compromised account. After fixing the issue, submit a delisting request through the blocklist operator’s lookup portal. Recovery can take anywhere from 24 hours to a few weeks, depending on the severity of the offense and how quickly you implement corrective measures.