How to Calculate Inbox Placement Rate and Improve It: Expert Tips and Strategies

The goal of email is to get your message where readers can see it – the inbox.

As of 2024, the average email deliverabilityⓘA sender’s ability to reach the recipient’s inbox with their outgoing emails. It may also describe the ratio of emails delivered to the inbox vs. those sent to spam or blocked by the receiving server. rate was around 83%. Some emails reach their destination, while many get sent to spam. Others will bounce back to the sender.

How can you gauge your inbox placement, and, more importantly, how can you improve it?

First, we need to know what it means.

Inbox placement is the percentage of emails that reach the inbox compared to other folders, such as spam, promotions, or updates. In other words, a “delivered” email doesn’t mean that it was delivered to the recipient’s inbox.

Email delivery rateⓘThe percentage of emails that are delivered to the intended recipient versus undelivered. is the percentage of emails that are delivered to the recipient mail server. Delivery rate is calculated as follows:

Number of emails delivered to the recipient server / total number of sent emails = delivery rate

Notice that the delivery rate refers to emails accepted by the recipient server but doesn’t specify the end destination. As long as your email reaches the mailbox and any of its available folders (promotions, spam, etc.), it’s considered delivered.

Inbox placement, also known as email deliverability, describes the percentage of emails that reach the inbox folder. By improving your email deliverability with the right tools and strategies, you can increase your inbox placement and overall campaign performance.

Belkins, a B2B lead generation agency, experienced poor inbox placement due to email deliverability issues. Their bounce rate rose to 19%, which led to the telltale symptoms of poor inbox placement: a lower sender scoreⓘOften used interchangeably with Sender Reputation. It is a score used by internet service providers to communicate your reputation with others based on your historical email-sending habits and behaviors. and poor engagement.

However, by implementing email validationⓘA process that determines if an email address uses valid syntax, exists on a given domain, and is configured to receive incoming email messages into their workflow, they quickly dropped their bounce rate to 0.4%. Addressing this primary email deliverability issue improved their engagement and cost-efficiency, demonstrating that their inbox placement rate was moving back in a positive direction.

You can calculate your campaign’s inbox placement rate by dividing the number of emails delivered to the inbox by the total number of emails sent.

(Number of inboxed emails / total number of sent emails) x 100 = Inbox placement rate

Inbox placement rate differs from the delivery rate as it specifically highlights emails placed in recipient inboxes. Note that it doesn’t include bounced emails, as it only compares the emails delivered successfully.

Here’s an example to help you differentiate your delivery rate from your inbox placement rate:

Campaign A results

• 10,000 emails sent
• 9,900 emails are delivered
• 9200 emails are delivered to the inbox

Campaign A delivery rate

(9,900 / 10,000) x 100 =99%

Campaign A inbox placement rate

(9,200 / 9,900) x 100 = 93%

Be aware that it’s impossible to know your exact inbox placement rate, as only service providers have access to this data. However, you can approximate the visibility of your emails by including a tracker like a UTM or a URL code snippet that identifies the source of user traffic. Adding a UTM to your email links can provide a basis for determining the visibility and effectiveness of your emails.

You can also determine the likelihood of inbox placement by using a tool like ZeroBounce’s Inbox Placement TestⓘA process that allows users to analyze how an email performs with various email service providers before sending the campaign to a real audience. The test identifies errors with the header, body, and footer to help users remedy problems that prevent them from reaching the inbox.. Here’s how it works:

1. Create a name for your test. Then, check the mailbox providers you wish to test. Nineteen are currently available, including popular worldwide names such as G-Suite, Hotmail, and Outlook.
   
   

   Select the mailbox providers to use when testing your inbox placement rate.

2. ZeroBounce will provide you with test email addresses for the selected providers. You’ll also get a unique code to add to the body.
3. Send your email to these addresses, and wait for the results.

You can calculate your campaign’s inbox placement rate by dividing the number of emails delivered to the inbox by the total number of emails sent.

The inbox placement test will automatically populate with your email’s inbox placement rate.

You can check the results for each provider better to understand the reasoning for your inbox placement rate so that you can make adjustments accordingly.

Various technical and behavioral factors directly impact your inbox placement as a mass sender. Here are the most important ones.

Sender reputation

Internet service providers use your sender reputation to assess your trustworthiness. A good sender reputation (around 90 or above) will result in strong inbox placement. Conversely, a poor sender reputation leads to increased spam placement and bounces.

Factors that lower your sender reputation include

• Email bounce ratesⓘThe percentage of emails that are undelivered vs. delivered to the intended recipient. exceeding 2%
• Spam complaint rates exceed 0.1%
• Excessive unsubscribe requests
• Low open and clickthrough rates

Inconsistent sending frequency

In addition to your reputation, ISPs look for predictable behaviors and patterns. If you don’t typically send mass emails but unexpectedly send a campaign to 100,000 recipients, your inbox placement rate will be low. You need to ramp up your sending volume gradually by sending emails in batches and tracking your performance.

Spammy content

ISPs look for patterns synonymous with spammy behavior. If your subject lines are misleading or contain certain keywords, it can trigger a spam filter. The impact of spammy words or phrases is typically more severe when combined with a poor sender reputation.

Historical engagement metrics

ISPs also look at campaign performance to determine the relevance of your emails to your audience. If subscribers are opening and clicking your emails, it’s safe to assume your emails are safe and relevant. As a result, your inbox placement rate improves.

Email authenticationⓘOne or more techniques or policies created to help internet service providers determine the identity of an email sender as legitimate. Examples of email authentication include SPF, DKIM, DMARC, and BIMI.

Major email providers like Google, Yahoo, and Microsoft require mass senders to use SPF, DKIM, and DMARC email authentication. These records authenticate your business and show cooperation with these providers to maximize user privacy and security. Providers directly state that using email authentication correctly will improve inbox placement over senders that do not.

Privacy Compliance

Depending on your location and the location of the recipient, you may not be permitted to send an email without direct consent. A primary example of this is the General Data Protection Regulation (GDPR) for EU nations. Emailing users who haven’t opted in can impact inbox placement rate, net you spam complaints, and even earn fines and penalties.

Mass senders must also clearly and visibly provide a one-click unsubscribe method. Failure to honor these requests promptly or continuing to email these addresses will quickly lower inbox placement rates.

Here are several must-follow tactics that every mass email sender must use to reach the customer inbox consistently.

#1. Clean and maintain a healthy email list

Your email list hygieneⓘThe act of or ability to maintain an email list or database consisting of valid and active email addresses. is the foundation of your email program. If your list contains invalid, fake, or outdated email addresses, expect high bounce rates and a poor sender score. Here’s how to fix it:

1. Upload your list to an email validation tool. The validator automatically detects and removes invalid or problematic emails, such as spam traps.
2. Remove the invalid and high-risk contacts, and upload your clean list to your ESP or CRM.
3. Repeat the validation process quarterly to combat email list decayⓘThe gradual degradation of a list’s average email address quality due to the expiration or abandonment of email addresses, as well as the collection of low-quality contacts over time..

Pro tip – Use a real-time email validation API on any data collection forms. The validator will alert visitors to typos in their email addresses and reject any fake or invalid emails that will result in bounced emails.

#2. Configure your email authentication and monitor compliance

Email authentication protocols, such as SPF, DKIM, and DMARC, are excellent ways to increase ISP trust and inbox placement. Creating these records is free, and your ESP may also assist with implementation.

1. Check with your ESP to determine if you already have an SPF or DKIM record enabled. If not, you can create both with a free generator tool.
2. Similarly, create a DMARC policy to instruct ISPs on how to handle non-compliant emails sent from your domain.
3. Use a DMARC MonitoringⓘA ZeroBounce service that helps users set up and configure DMARC, also known as Domain-Based Messaging, Authentication, and Conformance, which monitors outgoing emails and assists with email security. Users can actively monitor all outgoing emails sent from their listed domain. tool to ensure proper configuration. This service assists with configuring your DMARC policy, helping to secure your emails, and actively tracking emails sent from your domain and IP addresses.
   
   
   
   

   Monitoring your DMARC policy can help identify suspicious activity, such as spoofing and phishing, which can lower your inbox placement.

Pro tip – Monitoring DMARC complianceⓘDMARC (Domain-Based Messaging, Authentication, and Conformance). This describes whether or not an email successfully meets the standards described by the domain’s DMARC policy for SPF and DKIM email authentication. If an email satisfies the existing SPF or DKIM check, it’s considered DMARC compliant. can help identify two major inbox placement risks: misconfigured protocols and potential spoofing or phishing activity in your business domain. Your monitor will alert you to unusual activity and provide instructions on how to identify and remove potential threats.

#3. Warmup before you send more emails

Every sender can benefit from email warmupⓘA service that helps email senders improve their mailing domain and IP reputation by sending genuine email content to predetermined email addresses. Users will gradually increase the volume of emails sent while receiving positive engagement through an automated process.. This strategy can build a good sender reputation from scratch, repair damaged reputations, and boost inbox placement for existing domains.

1. Authenticate your domain with your chosen warmup tool.
2. Provide the tool with necessary information, such as the number of emails you typically send daily, weekly, and monthly.
3. Monitor your warmup progress by checking how many emails are sent to the inbox, spam, or go missing.
   
   
   
   

   Your email warmup statistics track your daily inbox placement rate over time.

Pro tip – If you don’t typically send mass email campaigns, warm up your email domain for at least one month. If you send using a cold domain, most emails will either bounce or go to spam. Trusting a provider to perform a proper email warmup will boost inbox placement rates and help avoid any risks to your sender reputation.

#4. Use a double opt-in method

Double opt-in confirmation assists with email list hygiene, but it also confirms subscriber intentions. Visitors commonly enter their email addresses into fields for promotions or offers but later have no recollection of signing up. This occurrence results in more inactive subscribers or spam complaints. Here’s how to do it:

1. Create a basic email autoresponder that triggers upon a new subscription.
2. Add a hyperlink to the body of the email along with a friendly message (e.g., “Hi User, please confirm your subscription to business@company.com.”). The user should be added to your primary mailing list.
3. When the user clicks the link, redirect them to a thank-you page with additional resources that might interest them.

Pro tip – It’s better to maintain a list of quality subscribers than to focus on quantity. Avoid holding on to contacts who show no interest for extended periods, as their lack of engagement negatively impacts inbox placement. You can also segment these inactive readers into other lists to experiment with new strategies.

#5. Switch to a different content strategy

Email marketing is a trial-and-error process. If your subscribers aren’t opening and engaging with your emails, stop sending the same types of emails. Here are some steps to consider:

1. Examine your latest promotional calendar. If you notice a high volume of recent promotions, curtail the need. Focus on value versus quantity to avoid oversaturation.
2. Consider how your company can help users. Use your knowledge and expertise to create insightful articles or exclusive reports that you can make available at no cost.
3. Pull from relevant industry news and share your insights on the topic with subscribers.
4. Segment your audience and create personalized sequences based on their position in the buyer’s journey. For example, a re-engagement sequence may help re-engage lapsed customers or inactive subscribers. Similarly, if a subscriber engages with an eBook or article, send related assets or information that can cater to those needs.

Pro tip – Automated sequences are excellent for nurturing subscribers no matter where they are in the journey. Brand and product education can be great for first-time buyers. On the other hand, new leads will benefit from general education, which can recognize their pain points and offer immediate solutions.

#6. Monitor your email blacklist status

Hundreds of email blacklist services exist online. If you unknowingly email a spam trap, experience high bounce rates or spam complaints, or show any activity deemed suspicious, you can end up on one.

1. Get a free blacklist monitorⓘA service that actively observes your email domain and IP address while comparing it to known email blacklists and antispam services around the internet. If a blacklist flags either the domain or IP, the monitor will notify the user. tool like ZeroBounce. It’s yours with a free account, and all you need to do is verify the domain and/or IP address you want to track.
2. Be on the lookout for notifications. The monitor will alert you when a blacklist entry is detected.
3. If you are blacklisted, respond swiftly. The notification will tell you who the provider is and provide instructions on how to request removal.
   
   
   
   

   Set up automated blacklist notifications to prevent inbox placement issues caused by anti-spam services.

Pro tip – Monitoring your sender reputation can also alert you to issues. Use a free tool like Google Postmaster Tools to track your sender score and stay up-to-date with resolvable issues.

#7. Manage subscriber content preferences

One of the best ways to encourage improved engagement metrics is to allow subscribers to change their content requests.

1. Create a setting to manage content preferences within the user account settings. Create logical categories for different content types, such as promotions, business news, or educational articles.
2. Your emails should include a link to user content preferences. An ideal place for this is in the footer near or around the unsubscribe link.
3. Segment subscribers into different mailing lists based on their selected preferences.

Pro tip – Professionals receive over one hundred emails daily. Segmenting your subscribers into specific mailing lists will help you create personalized content that stands out and is relevant to their interests. Tailor your emails to these lists, and continue monitoring campaign performance to keep your inbox placement rates high.

A condensed version of this article appeared in Entrepreneur Magazine in March 2021.