How to improve email deliverability: In-depth guide (2025)

Reading Time: 16 minutes

Achieving high email deliverability is essential for building trust, improving open rates, and driving conversions in email campaigns. Without it, even the best email content risks going unseen, derailing communication efforts, and wasting resources.

In this email deliverability guide, we will navigate common issues, offer tips to improve deliverability rates, and explore tools for ensuring success.

Email deliverability vs. email delivery

Email delivery and email deliverability are often used interchangeably, but there’s a key distinction between the two.

Email deliverability refers to the success rate of your emails reaching subscribers’ primary inbox folders, considering complex factors like domain authentication, IP reputation, and recipient engagement patterns. Think of it as the quality score that determines whether your email communications are treated as priority mail or junk.

Email delivery, on the other hand, tracks whether an email was accepted by the receiving server without being immediately rejected. It’s a binary metric — either the email was delivered to the server or it wasn’t. This surface-level measurement doesn’t account for where your email ultimately lands within the recipient’s inbox.

A 2024 study by EmailTooltester found that the average email deliverability rate across 15 email service providers (ESPs) was 83.1%. But it’s worth noting, that in reality it’s almost impossible to measure the deliverability rate of an entire ESP, so we suggest treating these results more as an educated guess. Nevertheless, while this suggested benchmark offers a safety net, falling below it can have cascading effects.

Poor email deliverability doesn’t just reduce open and click-through rates — it erodes subscriber trust. Indeed, users are more likely to distrust brands whose emails frequently land in spam. 

Worse, repeated issues can trigger long-term domain reputation damage. Plus, factors like less engaged audiences and frequent list churn negatively affect email deliverability. For example, low engagement signals (ignored emails or lack of clicks) train spam filters to sideline your emails, creating a cycle of diminishing returns.

That’s why it’s recommended to maintain high user engagement by sending relevant and valuable content to people who provided explicit consent to receive it.

How to improve email deliverability

Ensuring your emails successfully reach recipients’ inboxes requires several strategic steps. Here’s how to improve your email deliverability effectively:

1. Authenticate your emails
2. Build and maintain a clean email list
3. Monitor email engagement
4. Create high-quality content
5. Optimize sending practices
6. Test and monitor your deliverability
7. Comply with email regulations
8. Build a positive sender reputation
9. Use reliable email service providers (ESPs)
10. Provide value in every email

1. Authenticate your emails

Email authentication helps prevent spoofing, phishing, and spam-related issues that damage your sender reputation. To improve email deliverability, implement these key authentication protocols:

• SPF (Sender Policy Framework): Verifies that your emails are sent from authorized servers
• DKIM (DomainKeys Identified Mail): Uses cryptographic signatures to confirm email integrity
• DMARC (Domain-based Message Authentication, Reporting and Conformance): Provides instructions for handling unauthenticated messages, preventing domain abuse

For a step-by-step guide on implementing DMARC and securing your domain, check out this expert walkthrough:

2. Build and maintain a clean email list

A well-maintained email list helps you avoid spam complaints, high bounce rates, and disengaged subscribers. Here’s how you can keep your list clean:

• Use double opt-in: Ask subscribers to verify their email to confirm they want to receive emails from you
• Remove invalid or inactive addresses: Regularly clean your list to reduce bounces
• Avoid purchased or scraped lists: Don’t send emails to unverified users, as it harms engagement and your email sender reputation

3. Monitor email engagement

Mailbox providers consider engagement a key factor in determining a good email deliverability rate. To maintain strong engagement levels:

• Segment your audience: Use preferences and behavior data to create relevant email content
• Re-engage or remove dormant subscribers: Send targeted re-engagement emails and remove the subscribers who remain inactive
• Track open and click rates: Leverage advanced reporting to identify instances of low engagement, indicating potential deliverability issues

4. Create high-quality content

Well-crafted emails not only capture attention but also help avoid spam filters. To ensure your content provides value, adopt these best practices:

• Structure your emails with clear headlines, scannable content, and valuable information that encourages engagement
• Include proper HTML formatting, balanced image-to-text ratios, and mobile-responsive designs
• Ensure every email includes prominent unsubscribe options to maintain compliance and reduce spam complaints

5. Optimize sending practices

Your sending practices directly impact your email deliverability, so consistently follow these best practices for better results:

• Send emails from a consistent domain to build trust
• Avoid generic “noreply” addresses and opt for recognizable sender names 
• Determine optimal send times (when your audience is most active) and use them 
• Gradually warm up your email domain and new IPs to avoid volume spikes

6. Test and monitor your deliverability

Regularly testing email deliverability with tools like Mailtrap and Omnisend helps you identify and resolve inbox placement issues before they affect performance. 

Use these strategies to stay ahead:

• Monitor trends: Look at trends over time to find significant spikes or drops in metrics like opens, clicks, unsubscribes, complaints, and bounces
• Track bounce/complaint rates: Look for spikes above 2% (bounces) or 0.1% (complaints), as they require urgent list or content fixes
• Audit authentication: Regularly validate SPF/DKIM/DMARC with tools like MXToolbox to avoid sudden blocks
• Run inbox placement tests: Check if emails land in spam, promotions, or primary tabs across providers like Gmail 

7. Comply with email regulations

Strict adherence to email regulations protects your sender reputation, prevents legal issues, and builds trust while improving long-term email deliverability. To remain compliant:

• Follow GDPR, CAN-SPAM, and CASL laws: Obtain explicit consent before sending emails, and always include your business address
• Provide easy opt-out options: Ensure recipients can unsubscribe with a single click
• Honor unsubscribe requests promptly: Failing to do so can result in fines and blacklist penalties

8. Build a positive sender reputation

Your email sender reputation determines whether mailbox providers trust your emails. Indeed, a strong sender reputation is crucial for achieving optimal deliverability rates. To strengthen it:

• Monitor your domain and IP score: Use tools like Google Postmaster Tools to track your standing with ISPs
• Encourage subscriber interactions: Ask questions like, “Did this help?” to prompt replies and boost engagement signals
• Limit complaints: Segment lists to avoid irrelevant sends, have clear messaging, and always include unsubscribe links

9. Use reliable email service providers (ESPs)

Not all ESPs prioritize deliverability. You want to work with a reliable ESP, which you can identify by:

• Using deliverability optimization tools: Platforms like Omnisend offer list-cleaning, authentication support, and advanced analytics to enhance performance
• Checking reputation and compliance support: A trusted ESP helps manage authentication (SPF, DKIM, DMARC) and follows industry best practices
• Assessing scalability and reliability: Ensure the provider can handle your email volume without compromising deliverability rates

10. Provide value in every email

To improve email deliverability, send emails that provide value to your audience. Follow these best practices:

• Deliver relevant, engaging content: Ensure emails are informative and personalized based on subscriber preferences
• Balance promotions with value: Avoid excessive sales pitches — overly promotional emails reduce engagement and trigger spam filters
• Maintain a consistent brand voice: Recognizable and trustworthy messaging fosters long-term subscriber loyalty

How brands improved email deliverability: Real success stories

When it comes to email deliverability, it’s never just about hitting “send” and hoping for the best. It’s important to make sure your messages actually reach inboxes. And there are plenty of brands that actually struggle with this, often without realizing it until their engagement rates tank. 

But the good news is that there are many ways to improve email deliverability. Here are three Omnisend brands that turned things around:

1. AcreValue: From 5% to 70% open rates with better email practices

AcreValue, a farmland data and analytics platform, was dealing with a major deliverability crisis — open rates had plummeted to just 5%. It wasn’t until the brand’s own team stopped receiving emails that they realized something was seriously wrong.

“We initially found out about our deliverability issues by accident — our own team wasn’t receiving our emails,” says Ethan Rodriguez, Marketing Director at AcreValue. “That led us to investigate, and we discovered that both our domain reputation and IP reputation were as low as they could possibly be.”

What the brand did

• Refined segmentation: Focused on engaged subscribers to improve targeting and reduce spam complaints
• Fixed sending practices: Implemented sender authentication (SPF, DKIM, DMARC), cleaned its list, and sent emails on a consistent schedule.
• Implemented sunset automation: To ensure the list maintains of great quality, AcreValue automated contact re-engagement process

As a result, its open rates jumped from 5% to 70%, dramatically improving engagement and customer relationships.

2. 123Presets: Enhancing deliverability and doubling revenue

For 123Presets, a company selling Lightroom presets, poor deliverability meant lost sales. Emails weren’t reaching inboxes, cutting the brand off from its audience.

What the brand did

• Partnered with Omnisend to audit and improve its email marketing strategy
• Focused on deliverability best practices to ensure its emails consistently landed in inboxes

This resulted in a dramatic turnaround in deliverability — and an even bigger revenue boost.

“After we fixed the deliverability issues, our revenue doubled at least, compared to our last few months on Mailchimp,” says Tomas from 123Presets.

3. Kate Backdrop: Achieving a 1:300 ROI with omnichannel marketing

Kate Backdrop, a photography backdrop company, wasn’t just looking for better email deliverability — the brand wanted to maximize its entire marketing strategy.

What the brand did

• Omnichannel approach: Combined email with SMS campaigns to engage customers on multiple fronts
• Targeted automation: Set up workflows that kept subscribers engaged from the moment they signed up

With these practices the brand managed to achieve a staggering 1:300 return on investment (ROI) and better email deliverability, leading to higher engagement and more sales.

“Our welcome emails have the highest open and click-through rates among all our campaigns,” says Shan from Kate Backdrop. “They create a strong first impression and drive significant revenue.”

How to check email deliverability

To effectively check email deliverability and ensure optimal performance of your campaigns, follow these essential steps:

1. Monitor email engagement metrics
2. Check bounce rates
3. Verify email authentication
4. Analyze your sender reputation
5. Test email placement
6. Audit your email list
7. Check content quality
8. Evaluate sending practices
9. Monitor feedback loops
10. Conduct regular deliverability audits

1. Monitor email engagement metrics

Email engagement metrics, such as open rates, click-through rates, and unsubscribe rates, are strong indicators of email deliverability. 

If recipients frequently ignore or delete your emails, inbox providers may classify your messages as unwanted, harming your sender reputation. You want to: 

• Track metrics using your email service provider’s analytics dashboard
• Identify trends in recipient behavior to adjust your email strategy
• Experiment with subject lines and email timings to boost engagement

By consistently analyzing engagement, you can optimize your approach and improve email deliverability over time.

2. Check bounce rates

The bounce rate shows how many emails couldn’t be delivered to recipients. A high bounce rate can indicate problems with your email list or sending practices, affecting overall deliverability. There are two types of bounces: 

• Hard bounces occur when emails are sent to invalid or closed addresses, resulting in permanent delivery failure
• Soft bounces result from temporary issues, such as full inboxes or server problems

You must monitor both to maintain a healthy sender reputation. To avoid triggering spam filters or being flagged by ISPs, aim to keep your total bounce rate below 2%. Regularly cleaning your email list and removing invalid addresses can help.

3. Verify email authentication

Regularly verify that your SPF, DKIM, and DMARC records are properly configured and up-to-date. These protocols help receiving servers verify your identity and protect against email spoofing and phishing attempts. 

As part of your checklist:

• Implement SPF to verify or validate sending sources
• Use DKIM for encrypted and authenticated email content
• Set up DMARC to establish domain-level email policies

Proper email authentication builds trust with ISPs and enhances email deliverability. Simplify setup by using Omnisend’s SPF/DKIM/DMARC guide. 

4. Analyze your sender reputation

Your sender reputation is a crucial factor in determining whether your emails reach inboxes or get flagged as spam. Internet service providers (ISPs) assess your reputation based on engagement, complaints, and sending behavior. It’s prudent to:

• Check your sender score using tools like Google Postmaster Tools
• Pay attention to any sudden changes or declining trends that could indicate deliverability issues
• Monitor your domain and IP reputation scores across different email providers and reputation monitoring services
• Avoid sending emails too frequently or in large, irregular bursts instead of warming up your sender reputation and establishing a good cadence

If flagged, review email sending rules and practices, and avoid spam triggers.

5. Test email placement

Even if an email is delivered, it may land in the spam folder rather than the primary inbox or the promotions folder. Testing email placement helps you get an idea where your emails are being received, however, since it’s lacking actual engagement data from your real subscribers you should take the results with a grain of salt.

You can:

• Use email testing tools like GlockApps and Mail-Tester to check inbox placement across different ISPs
• Leverage seed testing tools to track delivery and assess placement across a network of test accounts 
• Adjust email formatting, sender name, and subject lines to optimize inbox visibility

By testing email placement regularly, you can refine your approach and improve email deliverability.

6. Audit your email list

A clean email list is essential for maintaining high email deliverability rates. Analyze your subscriber list quality by examining engagement history, age of subscriptions, and acquisition sources. 

An outdated or unengaged list with inactive or incorrect addresses can lead to bounces and damage your sender reputation. Here’s what you can do: 

• Examine hygiene factors like engagement history and last active date
• Use email verification tools to identify and remove problematic addresses
• Implement a double opt-in process to ensure valid signups
• Send a win-back campaign, then remove non-responders

Regular audits prevent list decay and ensure your emails reach interested recipients, improving deliverability and campaign performance.

7. Check content quality

Poor email content can trigger spam filters, so send relevant and high-quality emails free of spammy elements. It’s not just the quality of your messaging that matters — even the technical aspects do. You should: 

• Optimize HTML formatting and balance text-to-image ratio
• Avoid spammy words and excessive use of capital letters or exclamation marks
• Use relevant subject lines and valuable email copy to boost engagement
• Test every URL before sending to ensure there are no broken links and use only secured (HTTPS) URLs in your messages

Well-structured and relevant content increases the likelihood of reaching a recipient’s inbox.

8. Evaluate sending practices

Review your sending patterns and practices to ensure they align with industry best practices and ISP guidelines. Consistent, predictable sending behavior helps build trust with email providers and improves email deliverability. Make sure to: 

• Segment your audience to send targeted, relevant messages
• Ensure a consistent sending schedule with email automation to build trust
• Use a dedicated IP to isolate your reputation from others (for high-volume senders)
• Warm up new email addresses before sending large campaigns

9. Monitor feedback loops

Set up feedback loops with ISPs to receive notifications when recipients mark your emails as spam. This information provides insights into engagement trends and helps you identify and address any issues that may affect email deliverability.

You can use feedback loops to: 

• Track and analyze complaint data and adjust messaging accordingly
• Identify specific campaigns or segments that are causing issues
• Remove subscribers who frequently mark emails as spam

And if you’re using an ESP, they will handle the feedback loops setup. You just need to monitor the spam complaints in the reports provided by the ESP.

10. Conduct regular deliverability audits

Implement a comprehensive email deliverability audit schedule to regularly assess all aspects of your email campaign. These audits should combine technical, content, and engagement analyses to provide a complete picture of your deliverability health.

Email deliverability keeps changing from time to time. Routine audits can help you catch emerging issues before they escalate, so be sure to:

• Run deliverability tests using inbox placement tools
• Analyze engagement trends and optimize strategies
• Ensure compliance with email authentication protocols
• Review metrics, from bounce rates to spam complaints
• Align with evolving ISP rules, like Google and Yahoo’s sending requirements

Email deliverability tools

Several tools can help you check and monitor your email deliverability. Here’s a comparison of some popular options:

Tool	Strengths	Key features	Pricing
1. Omnisend	Comprehensive email marketing platform with built-in deliverability tools	Deliverability reports, Google Postmaster integration, built-in email list cleaning, dedicated IP options, subject line tester	Free plan available. Paid plans start at $16/month
2. Google Postmaster	Free tool for analyzing email performance via Gmail data	IP reputation, domain reputation, spam rate monitoring, authentication, and encryption compliance reports	Free
3. Mailtrap	Ideal for developers to test email functionality before sending	Email sandbox testing, spam score analysis, deliverability insights	Free plan available. Paid plans start at $14.99/month
4. MxToolbox	Powerful email diagnostics with a focus on blacklist monitoring	Blacklist check, SMTP diagnostics, SPF/DKIM analysis	Free plan available. Paid plans start at $129/month
5. GlockApps	Advanced deliverability testing for inbox placement analysis	Spam filter testing, email placement reports, authentication checks	Free trial available. Paid plans start at $85/month

While each tool serves a specific purpose, they differ significantly in their approach and specialization.

Tools like MxToolbox and GlockApps focus primarily on technical aspects and testing, while Google Postmaster Tools provides deep insights specifically for Gmail delivery. Mailtrap excels in development environments, so it’s best suited for developers needing pre-send testing.

Omnisend stands out by offering a comprehensive solution that integrates deliverability monitoring with actual email marketing capabilities. Unlike standalone tools that only diagnose issues, Omnisend provides monitoring and other solutions, from email list cleaning to scheduled Time Zone Optimized campaigns. 

With Omnisend, marketers can identify and resolve email deliverability issues without switching between multiple platforms. At the same time, they can also benefit from built-in best practices that prevent deliverability problems before they occur.

What is a good email deliverability rate?

While email deliverability (the percentage of emails reaching inboxes) isn’t directly measurable, marketers estimate it using engagement metrics like open rates and spam complaints. 

In contrast, the email delivery rate — the percentage of emails accepted by recipient servers — is tracked by ESPs. A high delivery rate (95%+) is essential, but it doesn’t guarantee inbox placement.

So, what is a good deliverability rate for email? Industry benchmarks suggest:

• Excellent: 95%+ (emails consistently land in primary inboxes)
• Good: 85-94% (minor spam filtering or promotions tab placement)
• Needs improvement: Below 85% (high spam risk or blocks)

Of course, these benchmarks vary by industry and email type. Transactional emails (order confirmations, password resets) are highly anticipated, often achieving 80%+ email open rates and superior deliverability. 

Marketing emails (newsletters, promotions) have lower engagement (15-25% open rates) and are more prone to filtering into spam. Optimizing sender reputation and engagement strategies is key to maintaining high email deliverability across all campaigns.

Common email deliverability issues

Understanding and addressing email deliverability issues is crucial for maintaining high inbox placement rates. Here are the most common challenges that can impact your email marketing deliverability:

1. Spam traps

Spam traps are email addresses set up by ISPs and blocklist providers to identify spammers or senders with poor email practices. They can be recycled addresses from abandoned email accounts or purpose-created addresses never used for subscription. 

Hitting spam traps can severely damage your sender reputation and trigger immediate deliverability problems.

2. High bounce rates

A bounce rate above 2% raises red flags. Hard bounces (invalid/permanent failures) indicate outdated lists, while soft bounces (temporary issues like full inboxes) suggest infrastructure problems. 

Consistently high rates degrade a sender’s credibility. Cut invalid addresses and monitor server health to stabilize your email deliverability rate.

3. Poor sender reputation

Your sender reputation score is like a credit score for email senders. Poor engagement metrics, spam complaints, and inconsistent sending patterns can damage this score. The result? Increased filtering and reduced inbox placement rates.

Adjust your sending practices by looking into email segmentation and tweaking your sending frequency to build a positive sender reputation.

4. Missing or incorrect email authentication 

Without SPF (verifies servers), DKIM (ensures email integrity), or DMARC (defines the handling of unverified emails), ISPs treat your campaigns as suspicious. Lack of authentication also exposes your domain to spoofing attacks and phishing attempts.

Many email clients now display prominent warnings to recipients when emails fail authentication checks. This can damage your brand reputation and reduce open rates.

5. Content triggering spam filters 

Email providers use sophisticated spam filters to block suspicious or overly promotional emails. Using spammy words like “free,” “guaranteed,” or excessive punctuation (e.g., “BUY NOW!!!”) can trigger these filters. 

Poorly formatted emails with heavy HTML coding, broken links, or missing text can also reduce deliverability. Even legitimate emails can face deliverability issues if they contain elements commonly associated with spam. 

6. Blocklisted domain or IP address

If your sending domain or IP address is blocklisted, your emails may be automatically rejected or sent to spam. Landing in spam databases like Spamhaus can block your emails right away. 

This can happen due to spam complaints, sending to invalid addresses, or failing to follow email marketing best practices. Check your email blacklist status using tools like MxToolbox and promptly follow delisting protocols if necessary. 

7. Inactive or unengaged subscribers

Subscribers who haven’t opened emails in six months or more drag down engagement metrics, signaling ISPs to deprioritize your sends. The chances of future inbox placement are reduced as ISPs categorize your emails as unwanted.

Low engagement rates also reduce your overall email marketing effectiveness. Regularly removing inactive users, re-engaging dormant subscribers, and segmenting lists based on activity levels can improve engagement. 

8. A sudden increase in sending volume

A sudden spike in email volume can trigger ISP filters, making your emails more likely to be throttled or blocked. Email providers monitor sending patterns, and abrupt increases can signal potential spam-like behavior. 

If you need to scale up email campaigns, it’s best to warm up your sending IP gradually. Slowly increasing volume over time helps establish credibility and prevents deliverability drops.

9. Lack of a clear unsubscribe option

Failing to include a visible and easy-to-use unsubscribe link can lead to higher spam complaints from frustrated subscribers. A missing unsubscribe option violates email regulations like CAN-SPAM and GDPR. 

Consider implementing a preference center that allows subscribers to adjust email frequency instead of fully unsubscribing. This can help retain engagement while positively impacting deliverability.

10. Poor list quality 

Purchased lists or unverified addresses are riddled with typos, role accounts (such as info@), and traps. These invalid entries and unengaged recipients inflate bounce rates and spam complaints, lowering inbox placement.

Additionally, purchased lists often contain outdated or unauthorized contacts, leading to compliance violations. Use double opt-in to verify interest and validate addresses before sending.

11. Poor sender name and email address configuration

Using inconsistent sender names, no-reply addresses, or frequently changing sending addresses can confuse recipients and ISPs. This inconsistency can trigger trust issues, reduce recognition, and impact engagement rates and deliverability performance.

Stick to a recognizable sender name, such as “Sarah from BrandX,” and use a verified domain aligned with SPF/DKIM protocols. This builds trust with both ISPs and subscribers.

12. Image overuse and lack of accessibility

Spam filters often flag emails with too many images and little text. Since some email clients block images by default, emails without ALT text may appear blank, reducing engagement. 

As well as this, visually impaired users rely on screen readers, making ALT text crucial for accessibility. Balance visuals with readable text and include ALT text for all images to improve accessibility and deliverability. 

Key takeaways

In this guide, we’ve discussed the critical aspects of email deliverability, a crucial factor in the success of any email marketing campaign. 

We’ve discussed how to check email deliverability by monitoring engagement metrics, bounce rates, and sender reputation. Additionally, we’ve outlined key strategies for improving email deliverability, including email authentication, list hygiene, and content quality. 

By implementing these best email deliverability practices and consistently monitoring your performance, you can ensure your emails reach their intended recipients. This, in turn, will help you drive engagement and achieve your marketing goals. 

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