Last updated
March 10, 2024

Maximizing Email Deliverability: Strategies and Best Practices

Brian Wu

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In the digital age, email remains a cornerstone of effective communication for businesses and marketers alike. However, the challenge of ensuring that these emails actually reach the intended inboxes—known as email deliverability—continues to be a pivotal concern. 

Whether you're looking to refine your existing email strategy or build a solid foundation for new campaigns, this blog will equip you with the knowledge and tools needed to achieve good email deliverability rates.


Understanding Email Deliverability

Email deliverability is a crucial metric for email marketers, digital marketing professionals, and business owners focused on optimizing their email campaign performance. At its core, email deliverability refers to the ability of an email to successfully reach the recipient's inbox. 

This capability is not just about avoiding spam filters but also ensuring that the number of emails being sent are welcomed and engaged with by recipients. Understanding the nuances of email deliverability can significantly impact any successful email marketing strategy.

Key Factors Influencing Deliverability

Several critical factors influence whether your email makes it to the inbox or gets lost in the spam folder. These include:

  • IP Reputation: The reputation of the IP address from which emails are sent. A poor reputation can lead to emails being blocked or filtered into spam.
  • Domain Reputation: Similar to IP reputation, but related to the domain name from which emails are sent.
  • Content Quality: Emails that appear spammy or contain certain keywords can trigger spam filters.
  • Sender Authentication: Protocols like SPF, DKIM, and DMARC help verify the sender's identity and are crucial for deliverability.

Difference Between Email Delivery and Deliverability

It's essential to differentiate between email delivery and deliverability. Email delivery refers to whether an email was successfully sent to the receiving server, without necessarily ensuring it reached the inbox. Deliverability goes a step further, focusing on the email's placement within the inbox versus the spam folder or not being delivered at all. 

Importance of Sender Reputation

Sender reputation is a vital component of email deliverability. ISPs (Internet Service Providers) and email services monitor the behavior and practices of senders to determine whether their emails should be delivered to the inbox. 

Factors that influence sender reputation include the volume of emails sent, how many recipients mark an email as spam, and the sender's adherence to email marketing best practices. Maintaining a good sender reputation is essential for ensuring that your emails reach their intended recipients.

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Strategies for Improving Email Deliverability

Improving your email delivery rate involves a multifaceted approach, focusing on both technical setup and content strategy. Here are some strategies and best practices to consider:

Best Practices for List Hygiene

List hygiene refers to the practice of regularly cleaning your email list to remove inactive, incorrect, or unengaged subscribers. Keeping your list clean minimizes bounce rates and improves your overall email engagement rates, which are critical factors for email deliverability.

  • Regularly Remove Inactive Subscribers: Identify subscribers who have not engaged with your emails over a specific period, typically six months to a year, and remove them from your list.
  • Use Double Opt-In: This method ensures that the people who subscribe to your list are genuinely interested in receiving your emails, reducing the chance of spammer complaints.
  • Verify Email Addresses: Implement email verification tools to catch and correct typos at the point of sign-up and eliminate invalid email addresses, including role-based email addresses, from your list.


How to Properly Authenticate Emails with SPF and DKIM

Email authentication is vital for proving that an email is not forged and comes from a legitimate source. SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) are two critical authentication methods that help improve your email deliverability.

  • SPF (Sender Policy Framework): SPF allows you to specify which mail servers are permitted to send email on behalf of your domain. Understanding what an MX record is can also help in this setup. To set up SPF, you need to add a specific TXT record to your domain's DNS settings that lists the IP addresses allowed to send emails from your domain. To check whether your IP address is blocked, you can refer to relevant sites such as DNS Checker or
  • DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to the header of your email messages. This signature is verified against a public key in your DNS records. To implement DKIM, you'll need to generate a DKIM key pair and add the public key as a TXT record in your DNS settings. Ensure your email service provider supports DKIM signing for your outgoing emails.

For better a understanding, watch this video on how to set up email authentication!

Tips for Maintaining a Strong Sender Reputation

Your sender’s reputation influences whether your emails will reach the subscribers’ inboxes or their spam folder. Here are tips to maintain and improve your sender reputation:

  • Monitor Your Sending Volume: Avoid sudden spikes in email volume, as this can trigger spam filters. Gradually increase your sending volume over time.
  • Engage with Active Subscribers: Focus your efforts on subscribers who regularly interact with your emails, and don’t try to get back people who have already unsubscribed. High engagement rates positively affect your sender’s reputation.
  • Promptly Address Complaints and Bounces: Remove email addresses that result in bounces and pay attention to spam complaints. ISPs track these metrics to evaluate your reputation.

Checklist for Email Deliverability Best Practices

  • Verify email addresses at sign-up to prevent invalid entries.
  • Implement double opt-in to ensure subscribers' genuine interest.
  • Set up SPF, DKIM, and DMARC records for email authentication.
  • Regularly clean your email list to remove unengaged or inactive subscribers.
  • Avoid sudden spikes in email volume to maintain a consistent sending pattern.
  • Use a reputable Email Service Provider (ESP) with high deliverability rates.
  • Segment your email list to send targeted, relevant content.
  • Personalize your emails to increase engagement.

To know whether your email deliverability strategies are up to the mark, take this quiz to find out!

Email Validation and Its Role in Deliverability

Email validation plays a pivotal role in enhancing email deliverability, a critical aspect of any email marketing campaign's success. Let's delve into how email validation influences deliverability rates and the best practices for implementing email validation processes.

The Connection Between Email Validation and Deliverability Rates

  • Reduces Bounce Rates: Invalid or non-existent email addresses lead to high bounce rates, which negatively impact your sender’s reputation. A poor email sender reputation can result in your emails being flagged as spam, thereby reducing deliverability. Email validation helps identify and remove these problematic addresses before you send your campaign, reducing bounce rates and protecting your reputation.
  • Enhances Engagement Rates: By ensuring that your emails are sent to valid addresses, email validation indirectly boosts engagement rates. Recipients who are active and interested in your content are more likely to interact with your emails, further improving your sender’s reputation and deliverability.
  • Avoids Spam Traps: ISPs and anti-spam organizations use spam traps (email addresses that are not used for communication but are monitored for spam) to catch malicious senders. Accidentally sending emails to spam traps can severely harm your deliverability. Email validation helps you avoid these traps by ensuring the addresses on your list are legitimate and active.

How to Implement Email Validation Processes

Implementing an effective email validation process involves several steps and best practices to ensure your email list is clean and your deliverability rates are optimized.

  • Use Email Validation Services: Numerous third-party services specialize in email validation (like Abstract's email validation API). These services can check your email list against known bad domains, validate email address formats, verify domain validity, and even check individual mailboxes in some cases. Incorporating such a service into your email campaign process is a straightforward way to improve deliverability.
  • Integrate Real-Time Email Validation at Sign-Up: To prevent invalid emails from entering your list from the start, integrate real-time email validation into your sign-up forms. This step can involve simple format checks, domain validation, and even real-time pinging of email servers to verify mailbox existence without sending an email.
  • Regularly Clean Your Email List: Periodically run your existing email list through an email validation process. This practice is essential for removing not just invalid emails but also addresses that might have become inactive over time. Regular list cleaning helps maintain a healthy sender reputation and improves email deliverability.

Monitoring and Testing Your Email Deliverability

Email deliverability is a critical factor in the success of your email marketing campaigns. This involves using various tools and techniques to test deliverability and understanding how to interpret key deliverability metrics. Some experts talk about the impact of email deliverability in the future. Here’s what you need to know:

Tools and Techniques for Testing Deliverability

  • Deliverability Testing Tools: Several specialized tools can help you test your email deliverability. These tools typically offer features like spam score analysis, inbox placement testing, and blacklist checking. Tools like Mail-Tester, ReturnPath, or Sender Score provide detailed insights into factors that might affect your emails' deliverability.
  • Seed Lists: A seed list is a list of email addresses used solely for testing the deliverability of your campaign. These email addresses should be spread across different email providers (Gmail, Yahoo, Outlook, etc.) to test how well your emails perform across different platforms. By sending your campaign to this list before the actual launch, you can get a good idea of where your emails are landing.
  • Engagement Tracking: Utilizing your email marketing software's built-in engagement tracking features can provide valuable insights into deliverability. Open rates, click-through rates, and conversion rates can all give clues about how well your emails are being received, although these metrics can be affected by other factors like content relevance and email design.

How to Interpret Deliverability Metrics

  • Bounce Rate: The bounce rate indicates the percentage of your emails that were not delivered to the recipient's inbox. A high bounced email rate could signal issues with your email list quality or with your sender reputation. There are two types of bounces to monitor: hard bounces (permanent delivery failures) and soft bounces (temporary delivery issues).
  • Open Rate: While not exclusively a deliverability metric, the open rate can indirectly indicate deliverability issues. If your emails are consistently not being opened across different campaigns, it might be because they are not reaching the inbox.
  • Spam Complaint Rate: This metric shows the percentage of recipients who marked your email as spam. High spam complaint rates can severely impact your sender’s reputation and deliverability. Keeping this rate as low as possible is essential.

Comparison Table of Common Email Deliverability Test Tools

Tool Name Features Price Range Mail-Tester Spam score, detailed feedback on potential issues Free for basic use; premium options available Sender Score Sender reputation score, IP reputation insights Free MXToolbox Blacklist checking, SPF, DKIM, and DMARC lookup Free for basic use; premium options available ReturnPath Inbox placement rates, competitive analysis Premium Litmus Spam testing, email previews, analytics Premium Email on Acid Deliverability testing, email previews, analytics Premium

Troubleshooting Common Deliverability Issues

Email deliverability issues can significantly impact the effectiveness of your email marketing campaigns. Understanding how to identify and resolve these issues is crucial for maintaining a healthy email program and abiding by legal laws.

Identifying and Resolving Issues with Spam Filters

Understanding Why Emails Get Marked as Spam

  • Content that looks spammy 
  • Lack of personalization
  • Poor sender reputation
  • Non-compliance with email authentication protocols (SPF, DKIM, DMARC)

Resolving Spam Filter Issues

  • Review and Adjust Your Email Content: Avoid using too many sales-oriented phrases, ensure a good text-to-image ratio, and personalize your emails to engage your recipients better.
  • Authenticate Your Emails: Set up SPF, DKIM, and DMARC records for your domain to verify your emails' authenticity.
  • Improve Your Sender Reputation: Send emails consistently and maintain a regular sending volume. Encourage engagement and promptly remove unengaged subscribers from your list.

Use a Reputable Email Service Provider (ESP): ESPs with good reputations can help improve your deliverability.

Dealing with Hard Bounces and Soft Bounces

Understanding Bounces

  • Hard Bounces: These occur when an email is permanently undeliverable, usually due to invalid email addresses or domains.
  • Soft Bounces: These are temporary deliverability issues, such as a full inbox or server downtime.

Resolving Hard Bounces

  • Clean Your Email List: Regularly validate your email list to remove invalid addresses. Consider using an email validation service to automate this process.
  • Monitor for Repeated Bounces: Some ESPs automatically manage bounces, but it's good practice to monitor for patterns or repeated bounces from certain domains and address these issues proactively.

List of Common Spam Trigger Words to Avoid

  • Financial Terms: Free, $$$, Earn $, Discount, Save, Credit, Loans
  • Urgency/Exaggeration: Act Now, Urgent, Don't Delete, This isn't spam, Once in a lifetime
  • Questionable Content: Miracle, Promise you, Satisfaction guaranteed, Risk-free, No catch
  • Call to Action: Buy, Clear, Give away, Order now, See for yourself
  • Miscellaneous: Winner, Amazing, Cancelling won’t be easy, Confidentiality, No obligation

Case Studies:


“Dmarcian made DMARC very simple to set up with examples and reporting that allowed me to monitor at first and work our way up to a 100% p=reject DMARC policy. The tools were easy to use and helped me build the SPF, DKIM and DMARC records to publish on our DNS.”

Frank Taormina, Assistant Director of Information Systems - Rockport, MA Government & Educational Services.

“After we implemented a DMARC reject policy, we saw phishing customer-service tickets drop by more than 70 percent.”

Thomas Bäcker, Head of Customer Security, Blocket.


Maximizing email deliverability is essential for the success of any marketing emails. With the right approach and tools, overcoming common deliverability challenges becomes manageable, leading to improved campaign performance, higher engagement rates, and stronger customer relationships. Remember, a commitment to best practices in email deliverability is not just about avoiding spam folders—it's about making meaningful connections with your audience.


What is the difference between a hard bounce and a soft bounce?

A hard bounce occurs when an email is permanently rejected due to reasons like an invalid email address or a non-existent domain. It indicates that the email cannot be delivered by any means. On the other hand, a soft bounce is a temporary issue, such as a full recipient's inbox or a server being down, suggesting the email could be delivered in the future once the issue is resolved.

How often should I clean my email list?

Cleaning your email list should be a regular part of your email marketing strategy. A good rule of thumb is to clean your email list every 3 to 6 months. However, the frequency can vary depending on your email sending volume and the rate at which you acquire new subscribers. Regular cleaning helps maintain high deliverability rates and engagement.

Can I improve deliverability for an old email list?

Yes, it is possible to improve deliverability for an old email list. Start by re-engaging inactive subscribers with a targeted campaign. Remove non-responders and hard bounces to clean your list. Implement email validation services to verify the validity of email addresses. Finally, ensure your email practices adhere to deliverability best practices, such as authenticating your emails and avoiding spammy content.

How can AI be used to enhance email deliverability?

AI can significantly improve email deliverability by optimizing subject lines for higher open rates, personalizing email content for each recipient to increase engagement, and predicting the best sending times to ensure emails are opened. Additionally, AI-driven analytics can identify patterns that lead to higher spam complaints or unsubscribes, allowing marketers to adjust their strategies accordingly.

How does user engagement impact email deliverability?

User engagement plays a crucial role in email deliverability. Email service providers (ESPs) track how recipients interact with your emails, including opens, clicks, and forwards. High engagement rates signal to ESPs that your content is valuable and relevant, which can improve your sender reputation and increase the likelihood of your emails being delivered to the inbox. Conversely, low engagement can lead to your emails being filtered as spam.

What are some strategies for segmenting an email list to boost deliverability?

Effective segmentation involves dividing your email list based on specific criteria such as demographics, past purchase behavior, or engagement levels. This allows for more targeted and relevant email campaigns. Strategies include:

  • Segmenting by activity, sending re-engagement campaigns to inactive subscribers.
  • Using demographics to tailor content that resonates with different groups.
  • Segmenting by purchase history to send personalized product recommendations.

Implementing these strategies can lead to higher engagement rates, thereby improving your overall email deliverability.

Brian Wu
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