Email Deliverability Guide: 16 Best Practices to Reach More Inboxes

Did you know that less than 80% of legitimate emails actually reach their final destination?

Email marketing is a very promising and effective way to sell goods and services. However, you can send a lot of emails and never get results if your emails aren’t delivered to recipients’ inboxes. Or, on a less drastic scale, if your email delivery is less than ideal, you will reduce the effectiveness of your campaign.

Practically speaking, emails are useless unless your audience actually receives them. In this case, a failure to receive the email can include your emails being relegated to the spam folder, in addition to those that bounce because the address is wrong.

But, what is the solution? Besides best practices for email composition, you want to ensure your email deliverability is optimal.

Compared to other types of digital marketing, email marketing has a technological infrastructure that needs to be understood to ensure email marketing success. For that reason, I have put together this comprehensive guide which I hope contributes to your have a more successful email marketing program.

What is Email Deliverability?

In a nutshell, email deliverability is the ability of your marketing emails to arrive in your recipient’s email boxes. You would consider emails delivered if they don’t get blocked or returned and end up anywhere besides the recipient’s spam folders.

There are several reasons why your email might not get delivered. One of the causes of non-delivery is that an ISP or email provider can decide that your promotional emails are actually spam. And, of course, having a lot of your emails marked spam by recipients can encourage this finding. Another reason is that your email list is out of date. To minimize this, you want to consistently cull your list so that the same addresses aren’t constantly returning your emails.

Why Does Email Deliverability Matter to Your Business?

Email marketing has the highest return on investment (ROI) compared to other marketing channels. For every dollar spent on email marketing, you get an ROI of $40. Of course, as a business, you should be doing email marketing. Not only is it highly effective, but it’s a very inexpensive marketing method. In other words, email marketing is accessible to almost any business.

Of course, the effectiveness of email marketing means that every email that bounces or lands in the spam folder is a lost opportunity. Similarly, the fewer emails that land in inboxes, the less ROI you receive because each email sent costs money. Therefore, a high level of email deliverability also improves overall ROI and saves money.

Email Deliverability Benchmarks: How Do You Compare?

To get a better understanding of email deliverability, here is one way of looking at what a “good” deliverabillity rate would look like based on industry best practices:

• 85–95% = Ideal deliverability rate
• 98–99% = Best-in-class brands
• Below 80% = Needs improvement

On average, 1 in 6 emails never reach the inbox due to spam filters, poor sender reputation, or blacklists. If your inbox placement rate is below 85%, you may need to optimize your email strategy.

Email Deliverability vs. Email Delivery

Many people confuse email delivery with email deliverability, but they are different concepts:

• Email Delivery refers to whether an email was accepted by the recipient’s server. Even if an email lands in spam, it still counts as delivered.
• Email Deliverability refers to whether the email actually lands in the inbox rather than spam or promotions.

Example: If you send 1,000 emails and 900 are accepted by recipient servers, your delivery rate is 90%. But if only 700 reach the inbox, your deliverability rate is 70%.

Here is a summary of these important differences to understand:

Feature	Email Delivery	Email Deliverability
Definition	Email is accepted by recipient’s email server	Email reaches the inbox, not spam
Affected by?	Bounced emails, invalid addresses	Spam filters, engagement, reputation
Measurement	Delivery rate (emails not bounced)	Inbox placement rate

How Does Email Deliverability Work?

It works by getting your content into the boxes of your audience. To accomplish high email deliverability, you need to maximize each step in the process. You also need to maximize each of the delivery factors, which we’ll talk about in the next section. For now, let’s focus on the email delivery process.

4 Components of an Email Delivery Process

For most of us, sending an email comes automatically — simply click compose in your email client, type or paste what you want to say, add recipients and subject lines, and click send. For commercial emails, it’s a little more complicated. Not only do you need to create content that will appeal to more than one person, but understanding the overall process will help you master what’s needed to maximize email deliverability.

1. Email Sender

First, all emails originate with an email sender. Essentially, this is any business sending out emails as a part of an email marketing campaign. Non-bulk or non-marketing emails, especially those that are sent individually, are not the ones that we’re discussing here. That’s because deliverability is primarily an issue when you send a large volume of emails at once.

2. Email Service Provider

Email service providers, or ESPs, are third parties that help you with your email marketing and automation. Typically, businesses will use these services to send and receive the emails themselves. Examples include Gmail, Yahoo, and Outlook. Your ESP will also let you send out one-off emails.

For recipients, the ESP shows up as the “@” portion of your email address.

If you were curious, ActiveCampaign ranked #1 in email deliverability among competitors in EmailToolTester’s deliverability test, achieving an average deliverability rate of 89.6%.

3. Gateways

Gateways are companies (platforms) that help you send emails. There are several types of gateways, many of which will also help determine your email delivery. In other words, they can be more than just a way to send and receive emails. Strictly speaking, your ESP is a gateway as well. Other gateways include your internet service provider (ISP), anti-spam systems, blacklisting organizations, and the recipients’ spam filters.

In order to have your email delivered, you need to pass through each of these gateways. Many of them can “veto” email delivery, classify them as promotional, or relegate emails to the spam folder. Therefore, it’s important that these companies understand that your company is reputable.

4. Recipients

Finally, your subscriber or customer is the recipient of each email. Overall, the goal of deliverability is for all of your intended recipients to receive the email, with the exception of newly disconnected addresses. That’s because if an address has recently been disconnected, you haven’t had time to take it off your list. This interval should be as short as possible.

The 6 Main Factors that Impact Email Deliverability

Now that we understand the basics of getting your emails delivered let’s talk about the different factors that help get yours into that inbox. This way, it’ll be easier to understand how we can boost email deliverability for maximum ROI.

1. Sender’s Reputation

This is assessed by your ISP. They perform a reputation check and score you on a scale of 0-100 to figure out if you are a legitimate business. If your score is low, your email is unlikely to make it to your recipient’s inbox. Instead, your emails will likely end up in everybody’s spam folders.

But what goes into a sender’s reputation? One of the biggest drivers of a positive or negative reputation is the extent to which your emails are actually delivered. This means that email addresses that bounce should be removed right away. Likewise, higher open rates are helpful to your reputation, while a large number of spam reports are harmful. We will talk about best practices in the next section.

2. Engagement

Engagement is how the recipients respond to your email – whether they open it, ignore it, spam it or unsubscribe. ISPs monitor the engagement. For this reason, positive engagement helps your emails get delivered, while negative engagement makes them more difficult. One reason that these metrics are so useful is that they don’t require an email provider to “read” every email in order to police spam. Instead, they use subscriber behavior to judge whether or not a sender is trustworthy.

3. Spam Filters

This is the software that’s used by ISPs to scan incoming messages. It can either mark your message as spam or allow it through. A rate of 0.02 percent spam flagging is enough to cause delivery issues. Therefore, even if your emails are top-notch, only a few customers marking your email as spam can cause significant email deliverability issues.

4. Email Bounces

When you send an email to an invalid email address, the email bounces. If your bounce rate is high, it will directly impact your sender’s reputation and future email deliverability. Emails can either soft bounce or hard bounce. A soft bounce happens when too much email is going to the system at any given time, and the email software or ISP wants to reduce traffic temporarily.

A hard bounce happens when an email was no longer being used and has been disconnected. Hard bounces should result in that address being removed from your list immediately. This is one of the best ways to manage your bounce rate.

5. Email Content

Emails need to contain content that is relevant to your intended recipient. This includes the subject line, body text and supporting images, and links. Certain words may also trigger spam alerts and send your email straight to the spam folder. Some easy examples include all caps, funny fonts, scammy words, and others that appear to solicit information from the recipient.

However, there’s more to having good email content than just words. Email codes like <embed> tags or JavaScript that are malicious can also impact your deliverability. Also, if the URLs in your email link to sites with a poor reputation, your deliverability will take a direct hit. In other words, ISPs try to keep consumer inboxes safe from scams and malicious content. Fortunately, unless your company’s computer system gets infiltrated by a virus, this shouldn’t be a problem for legitimate businesses.

6. Blacklists

Emails sent from blacklisted servers or domains will never make it to the inbox. Simply put, blacklists are real-time databases kept by ISPs and email providers. These lists identify domains and servers that send emails flagged by spam filters.

It’s relatively easy to get placed on a blacklist. For instance, if too many people report your emails as spam, it can land you on a blacklist. The same thing goes with sending too many emails too fast or buying pre-made email address lists. Again, the careful use of best practices helps companies avoid blacklists when at all possible.

How to Avoid Spam Traps & Blacklists

On the topic of blacklists, it’s important to go over the existence of spam traps.

Spam traps are fake email addresses used by ISPs to catch senders with bad email hygiene. There are two types:

• Pristine Spam Traps – Addresses never used by real people (indicates poor list-building).
• Recycled Spam Traps – Old email addresses repurposed to catch bad senders.

How to check if you’re blacklisted?

• Use MXToolbox Blacklist Check to see if your IP is flagged.
• Monitor Google Postmaster for negative reputation signals.

Further Reading: How to Create the Perfect Content for Your Email Marketing

Email Authentication & Infrastructure: The Foundation of Deliverability

Before proceeding into my recommended best practices, its important to understand some of the technology and keywords to understand to help improve email deliverability rates and improve your domain reputation.

One of the biggest factors determining whether your emails land in inboxes or get lost in spam filters is email authentication and infrastructure. Email providers like Gmail, Outlook, and Yahoo use filtering systems to detect spoofed, fraudulent, or low-reputation senders. Without proper authentication, even legitimate businesses can see their emails flagged as spam.

This section covers three essential authentication protocols—SPF, DKIM, and DMARC—the role of IP reputation, and how to optimize email infrastructure for maximum deliverability.

Email Authentication: SPF, DKIM, and DMARC

To protect against phishing, spoofing, and spam, mailbox providers rely on three key authentication protocols. Implementing these correctly improves both email security and deliverability.

SPF (Sender Policy Framework) defines which mail servers are authorized to send emails on behalf of your domain. Without SPF, spammers can forge your domain to send fraudulent emails. To set up SPF, a TXT record must be added to your domain’s DNS settings. It should specify which servers are permitted to send emails, such as those from your email marketing platform.

DKIM (DomainKeys Identified Mail) adds an encrypted digital signature to outgoing emails, allowing ISPs to verify that the message was not altered in transit. To implement DKIM, a public key is added to the domain’s DNS settings through your DNS provider, and the private key is managed by the email service provider.

DMARC (Domain-based Message Authentication, Reporting & Conformance) works alongside SPF and DKIM to provide instructions on how email providers should handle messages that fail authentication. A DMARC policy can be set to monitor, quarantine, or reject unauthenticated emails. Setting up DMARC also enables reports on authentication failures, helping businesses improve security and trust.

IP Reputation: Shared vs. Dedicated

Mailbox providers track sending behavior to determine whether an IP address is trustworthy. A poor IP reputation increases the likelihood of emails being marked as spam.

Shared IPs are used by multiple senders and are maintained by email service providers to ensure consistent deliverability. They are a good option for businesses with low email volumes, but reputation depends on all senders sharing the IP.

Dedicated IPs are assigned to a single sender, allowing full control over reputation. However, they require an IP warming process, where sending volume is gradually increased over time to build credibility with mailbox providers. Dedicated IP addresses are best for high-volume senders exceeding 100,000 emails per month.

Optimizing Email Infrastructure

Using a reputable email service provider (ESP) with strong deliverability practices is essential. Providers such as SendGrid, Mailgun, Amazon SES, and Postmark offer email deliverability tools to manage email performance and authentication.

Monitoring blacklists and reputation scores helps identify deliverability issues before they impact campaigns. Services like MXToolbox and SenderScore allow businesses to check their domain’s standing and take corrective action if necessary.

Reverse DNS (PTR records) should also be set up to ensure receiving servers can verify the sending domain. Without reverse DNS, emails may be rejected or classified as spam.

Taking these steps strengthens email deliverability, improves inbox placement rates, and ensures marketing campaigns reach their intended audience.

How to Test and Monitor Email Deliverability

Even the best email strategy can run into deliverability issues. Regular testing and monitoring help catch problems before they affect inbox placement, ensuring your emails reach subscribers.

1. Use Deliverability Testing Tools

Several tools analyze email performance before you send campaigns:

• Mailtrap: Simulates real email sending to detect issues.
• GlockApps: Tests spam filtering across email providers.
• Mail-Tester: Assigns a deliverability score based on spam triggers.
• Sender Score: Measures sender reputation, affecting inbox placement.

Running these tests helps you optimize emails for better delivery.

2. Track Key Performance Metrics

Email metrics provide insights into deliverability. Monitor:

• Bounce rate: Keep below 2% to avoid domain blocks.
• Open rate: Low rates may indicate filtering issues or weak subject lines. Be careful if you are below 20%.
• Click-through rate: Declining CTR suggests unengaging content.
• Spam complaints: If complaints exceed 0.1%, ISPs may filter your emails.

Regularly reviewing these helps identify and fix deliverability problems.

3. Check Blacklists and Reputation Scores

If your domain or IP is blacklisted, emails may never reach inboxes. Tools like MXToolbox, Spamhaus, and Blacklist Checker help detect and resolve blacklist issues. Google Postmaster Tools and Microsoft SNDS provide insight into how ISPs perceive your emails.

4. Test Inbox Placement

Inbox placement testing shows where your emails land—Primary, Promotions, or Spam. If too many land in Promotions or Spam, adjust your sender name, email frequency, or content to improve placement.

5. Use Seed Lists for Testing

Seed lists are test email addresses across different providers, allowing you to spot issues with formatting, delivery, or filtering before launching a campaign. Many ESPs offer seed list testing as part of their services.

Regular testing and monitoring ensure consistent deliverability, helping you maintain inbox placement and engagement.

16 Email Deliverability Best Practices

Now you understand why email deliverability is so essential for maximizing the effectiveness of your email marketing efforts. By following these best practices, you can improve inbox placement rates, maintain a strong sender reputation, and ensure your emails reach engaged subscribers.

Further Reading: Looking for Email Marketing Templates? Here are My Top 15 Recommendations

1. Keep Email Content Clear and Concise

Long, wordy emails can trigger spam filters and reduce engagement. Write clear, to-the-point messages that provide value upfront. Use a balance of text and images, and avoid excessive formatting or large attachments.

2. Authenticate Your Emails

Ensure proper email authentication with SPF, DKIM, and DMARC to prevent spoofing and phishing attacks. These protocols establish trust with mailbox providers and improve inbox placement rates.

3. Monitor and Improve Your IP Reputation

Your sender reputation directly impacts deliverability. Whether using a shared or dedicated IP, monitor performance with tools like Google Postmaster Tools and SenderScore, and avoid sudden spikes in email volume.

4. Set Up and Maintain MX Records

MX (Mail Exchange) records ensure email servers recognize your domain as a valid sender. Without them, your emails may be blocked or filtered. Regularly check your domain’s MX records to maintain proper email routing.

5. Make Unsubscribing Easy

A clear unsubscribe link reduces spam complaints and improves list hygiene. Use a one-click unsubscribe option and offer preference management, allowing recipients to control the types and frequency of emails they receive.

6. Personalize Your Emails

Emails with personalized subject lines and content have higher open and engagement rates. Use subscriber data to customize emails based on name, behavior, or interests to increase relevancy.

7. Separate Transactional and Marketing Emails

Use different IPs and subdomains for transactional and marketing emails to protect deliverability. Transactional emails, like order confirmations, should have higher inbox placement rates, while marketing emails may be filtered differently.

8. Ask Subscribers to Whitelist Your Emails

Encourage recipients to add your email to their contacts or safe sender list to bypass spam filters. Include this request in your welcome email for the best results, and remind them to add your emails to their primary inbox if they are a Gmail user.

9. Use Both HTML and Plain Text Versions

Providing a plain text alternative improves deliverability and ensures your email is accessible on all devices. Many spam filters flag emails that contain only HTML without a plain text counterpart.

10. Implement Double Opt-in

Double opt-in reduces spam complaints and improves engagement by requiring users to confirm their subscription before receiving emails. This extra step ensures only interested recipients are added to your list.

11. Segment Your Email List

Divide subscribers into targeted segments based on demographics, engagement levels, or purchase behavior. This helps tailor content for higher open and click-through rates, improving deliverability. Email marketers who segment their lists see a 39% increase in open rates, making targeted messaging a key strategy for improving engagement.

Further Reading: 12 Ways How to Improve Your Email Open Rate

12. Remove Inactive Subscribers

High bounce rates and low engagement harm sender reputation. Regularly remove inactive subscribers or create re-engagement campaigns before removing them completely.

13. Validate Email Addresses Regularly

Use tools like NeverBounce, ZeroBounce, or BriteVerify to identify and remove invalid or risky email addresses before sending campaigns. This reduces bounces and improves deliverability.

14. Optimize Text-to-Image Ratio

Emails that are too image-heavy are often flagged as spam. Aim for a 60:40 text-to-image ratio to maintain readability and avoid triggering spam filters.

15. Check Spelling and Avoid Spam Trigger Words

Poor grammar and spelling reduce credibility and increase spam risk. Also, avoid overly promotional words in your subject line like “free,” “guaranteed,” or “urgent.”.

16. Avoid Spammy Formatting and Attachments

Using all caps, excessive punctuation, or attachments can flag emails as spam. Instead, link to hosted files on your website or cloud storage to reduce filtering risks.

Email Deliverability Best Practices Summary

Best Practice	Why It Matters	How to Implement
Keep Email Content Concise	Avoids spam filters, improves engagement	Write clear, relevant messages with minimal fluff
Authenticate Emails (SPF, DKIM, DMARC)	Boosts trust with mailbox providers	Configure authentication in DNS settings
Monitor IP Reputation	Prevents email blocking and filtering	Use Google Postmaster Tools, SenderScore
Set Up MX Records	Ensures email routing works properly	Regularly check and update MX records
Make Unsubscribing Easy	Reduces spam complaints	Use a visible one-click unsubscribe link
Personalize Emails	Increases open rates and engagement	Use names, behaviors, or preferences
Separate Transactional & Marketing Emails	Protects deliverability of crucial emails	Use separate IPs/subdomains
Ask for Whitelisting	Bypasses spam filters	Request in welcome email
Send HTML & Plain Text Versions	Improves accessibility and inbox placement	Enable both formats in email settings
Use Double Opt-In	Reduces spam complaints	Require users to confirm subscription
Segment Email Lists	Improves targeting and engagement	Group subscribers by behavior and interest
Remove Inactive Subscribers	Improves list hygiene and reputation	Create re-engagement campaigns, then prune list
Validate Email Addresses	Reduces bounce rates	Use email verification tools
Optimize Text-to-Image Ratio	Avoids spam filtering	Maintain 60:40 text-to-image ratio
Check Spelling & Avoid Spam Words	Prevents spam classification	Proofread and use neutral language
Avoid Attachments & Spam Formatting	Prevents filtering and security concerns	Link to hosted files instead

By following these best practices, you can strengthen your email deliverability, maintain a high sender reputation, and ensure your messages consistently reach subscribers’ inboxes. Regular monitoring, authentication, and engagement-focused strategies will help optimize your email campaigns for long-term success.

Further Reading: 7 Best Ways to Build an Email List (From Scratch)

What NOT to Do for Higher Email Deliverability

Finally, let’s look at a few practices you should avoid for the best email deliverability results. Many of these are counterpoints to the best practices discussed above.

• Don’t send emails from your free personal email. Not only is it unprofessional, but it’s a good way to get your personal email blacklisted, banned, or even closed. Personal emails are not intended for sending bulk commercial messages.
• Don’t use spam trigger words like losing weight, help, urgent, free, 100%, etc. in your email subject line. Instead, when these words are actually necessary, put them in the body of the text. However, you’ll find that unless your legitimate business is related to those terms, you’ll rarely need them.
• Don’t use URL shorteners. For some reason, URL shortener use can serve as a red flag. However, the body of your email has plenty of space for a full URL, and these provide transparency about where you’re sending your subscribers.
• Don’t buy email lists or scrape emails from the web. There are a couple of reasons for this. First, in some jurisdictions, this practice may be illegal, such as with the CAN-SPAM Act. Second, email lists can be very low quality. Not only do they frequently include a lot of invalid emails, but they’ll also include some spam traps. A spam trap is a fake email address maintained by keepers of blacklists. In other words, scraping and purchasing lists are a great way to get blacklisted.
• Don’t use Caps in your subject line or the email body copy. Once again, it’s unprofessional and sloppy. Acronyms are okay to use as appropriate, but besides this, you should remember that CAN be construed as shouting. It’s another mistake that spammers frequently make.
• Don’t embed forms or include attachments unnecessarily. This can cause your emails to consume a lot of data. Use attachments when you need to, but this is usually the case with transactional emails. You don’t want to look like a data harvester, either.
• Don’t email users that have bounced constantly. Not only does the email address likely not exist anymore, but high bounce rates reduce your quality scores with ISPs and ESPs. Both of these issues can reduce your email deliverability.

How to Test Email Deliverability?

Finally, it’s always important to gauge your brand’s email deliverability. By far, the easiest way is to use tools to run email deliverability tests. Providers include Senderscore, Glock apps, SenderPost, and Mailtrap. Each of these tools has different features, but they’ll all tell you how well your emails are performing. Then, you can figure out how to improve your email delivery and boost the ROI of your campaigns.

Final Checklist for Quick Takeaways

Use this checklist to ensure your email campaigns achieve maximum deliverability and inbox placement.

Email Authentication & Infrastructure

✅ Set up SPF, DKIM, and DMARC authentication to improve trust with ISPs.
✅ Choose between a shared or dedicated IP based on your email volume and reputation goals.
✅ Regularly monitor your sender reputation using Google Postmaster Tools and Sender Score.

Email List & Audience Management

✅ Use double opt-in to confirm subscriber interest and improve engagement.
✅ Remove inactive subscribers regularly to maintain a clean list.
✅ Validate email addresses with tools like NeverBounce or ZeroBounce to reduce bounce rates.

Email Content & Formatting

✅ Write concise, relevant content that avoids spam trigger words.
✅ Maintain a 60:40 text-to-image ratio to prevent filtering issues.
✅ Provide plain text alternatives for better accessibility and spam filtering.

Sending Practices & Engagement

✅ Segment your list for personalized, relevant email campaigns.
✅ Avoid sending emails too frequently to prevent spam complaints.
✅ Use A/B testing for subject lines and content to improve open rates.
✅ Make it easy to unsubscribe with a one-click option.

Testing & Monitoring Deliverability

✅ Regularly check blacklist status with MXToolbox and Google Postmaster.
✅ Run deliverability tests using Mailtrap, GlockApps, or Mail-Tester.
✅ Track key metrics:

• Bounce rate: Keep below 2%
• Spam complaint rate: Keep below 0.1%
• Open rate & click-through rate: Higher engagement = better deliverability

By following these steps, you’ll improve inbox placement, strengthen your sender reputation, and maximize the effectiveness of your email campaigns.

The Final Word on Email Deliverability

Whether you have a large business or a small one, you should be doing some level of email marketing. However, even the best emails are only as good as your ability to have them delivered to recipients. That’s why we spend so much time and effort working on email deliverability. Whether it’s carefully crafting your emails, using optional features like MX records and third-party verification, or building your email list the right way, you will find the effort worthwhile.