What is An Inbox Placement Rate and How To Calculate It?

When creating an email campaign, what's your number one concern? A perfect email copy? Or an enticing subject line? Or the best CTAs? Ever wondered what happens if your emails don't even reach the intended recipients' inboxes?  I'm not saying this, but studies are. 1 out of 6 marketing emails never reach the inbox. In fact, the average email deliverability rate in 2024 across 15 ESPs tested was 83.1%. That means a whopping 16.9% of these emails never reach the intended recipients' inboxes.

Before you lose sleep over perfecting your email itself, consider this: the most critical factor is ensuring your message gets delivered. This is where Inbox Placement comes in.

Let's delve deeper into what inbox placement is and how to calculate it, as well as explore strategies to improve your inbox placement rate (IPR). By optimizing your IPR, you can finally guarantee your carefully crafted emails reach the inboxes they deserve.

What is Inbox Placement?

Inbox placement refers to emails that successfully land in the main or primary folder of any mailbox. It defines what happens to your emails once they land in the recipient’s mailbox—whether they land in the inbox, spam, promotions, social, or any other folder. 

The number of emails that land in the inbox and not in spam out of the total number of emails delivered defines the inbox placement rate (IPR). So, IPR is an important email marketing KPI (key performance indicator) that defines how well your emails land in the recipient's primary folder. 

Let’s say you are running an email marketing campaign. You sent 5000 emails, out of which 4,500 were successfully delivered. Now, out of these successfully delivered emails, 3600 have landed in the inbox. So, your inbox placement rate would be 80%.

How Does Inbox Placement Affect Email Deliverability? 

Inbox placement is crucial for the success of your email marketing campaigns. 

If your emails make it to the mailbox but end up in spam, junk, promotion, or similar tabs, they have little to no chance of being seen at all. 

On the other hand, when emails land in your inbox, your subject line, header, etc., entice the user to open them. 

A low inbox placement rate will eventually result in low opens, clicks, and replies.

What Is The Difference Between The Inbox Placement Rate and Delivery Rate?

Both Inbox Placement Rate (IPR) and Delivery Rate are important metrics in email marketing, but they tell you different things about your email's success. Here's a breakdown:

• Delivery Rate: This is a broader measure that simply tells you what percentage of your emails were successfully delivered to the recipient's mailbox.

It doesn't distinguish between the inbox and spam folders.

A high delivery rate (usually above 90%) indicates a good reputation with email servers and minimal bounce rates.

• Inbox Placement Rate (IPR): This metric focuses specifically on emails that landed in the recipient's primary inbox rather than spam or promotions folders.

A good IPR (ideally over 70%) suggests your emails are relevant and engaging to recipients, and email providers trust you as a sender.

How To Calculate Inbox Placement Rate?

Inbox Placement Rate (IPR) tells you the percentage of emails that reached your recipients' inboxes compared to the total number of emails delivered. Here's how to calculate it:

Formula:

IPR = (Emails Delivered to Inbox) / (Total Emails Delivered) x 100%

Points to Consider:

• Exclude Bounces: Bounced emails never reach the recipient's mailbox, so they shouldn't be included in the calculation. Focus on emails that were successfully delivered.
• Identify "Inbox" Emails: You'll need a way to track how many emails landed in inboxes. This might involve seed list tracking, where you send test emails to a list of email addresses across different providers (Gmail, Yahoo, etc.) and manually check where they land. Many email marketing platforms provide IPR data as part of their analytics.

Example:

Let's say you send an email campaign to 1,000 subscribers. Out of those:

50 emails bounce.

900 emails are delivered.

Among delivered emails, you check your seed list and find 780 landed in inboxes.

Calculation:

Total Emails Delivered = 1,000 emails - 50 bounces = 950 emails

Emails Delivered to Inbox = 780 emails

IPR = (780 emails / 950 emails) x 100% = 82.1%

In this example, your Inbox Placement Rate is 82.1%.

Factors That Affect Inbox Placement

By now, you have understood that inbox placement is crucial for the success of your email campaigns. But have you ever wondered what factors affect the ability of your emails to land in your inbox? Or, what makes your emails land in spam folders and not in your inbox folder? 

Let’s look at all these factors: 

1) Sender Reputation 

Sender reputation is a crucial factor influencing where your emails land – inbox or spam folder. Mailbox providers (Gmail, Outlook, etc.) use complex algorithms to assess a sender's reputation, and a good reputation significantly increases your chances of reaching inboxes.

A positive sender reputation signifies you're a legitimate sender with valuable content. This builds trust with mailbox providers and recipients, leading to higher inbox placement rates.

Various factors can negatively impact your reputation and lead to emails landing in spam. These include:

• High Complaint Rates: If recipients frequently mark your emails as spam, it raises red flags.
• Poor List Hygiene: Sending emails to invalid or unengaged addresses can be seen as spammy behavior.
• Spam Trap Hits: Spam traps are email addresses specifically used to catch spammers. Accidentally sending them hurts your reputation.
• Inconsistent Sending: Frequent changes in sending volume or content can appear suspicious.

2) Email Infrastructure 

Email infrastructure plays a significant role in where your emails land – inbox or spam folder. 

Different aspects of your infrastructure can influence inbox placement.

For example, shared IPs are used by multiple senders, and the reputation of one sender can affect others. If someone using the same IP sends spam, it can hurt your deliverability. Dedicated IPs offer more control and reputation building, but come at a higher cost. This is the reason why In Smartlead, we use dedicated IPs for sending emails.

Additionally, new IPs need to be "warmed up" by gradually increasing email volume to establish a positive reputation. Sending a high volume of emails from a new IP can raise red flags.

The reputation of the email marketing platform you use can also influence your sender score. Choose a reputable platform with a history of good deliverability, like Smartlead. Our clients are running successful campaigns and generating as many as 150,000 leads per month.

3) Email Sending Frequency 

Email sending frequency can definitely impact your inbox placement. It's all about finding the right balance to keep recipients engaged without overwhelming them.

If you bombard recipients with emails, they're more likely to mark them as spam. This can significantly hurt your sender reputation and lead to future emails landing in spam folders.

Some mailbox providers might filter emails from senders who send too frequently, assuming they're more likely to be spam.

4) Personalization and Segmentation 

Personalization and segmentation go hand-in-hand, and both have a positive impact on inbox placement.

Personalized emails with content tailored to recipient interests are more likely to be opened and engaged with. This tells mailbox providers that recipients find your emails valuable, which is a key factor in inbox placement.

Segmentation ensures recipients receive emails relevant to their needs and preferences. This creates a more positive user experience, reducing the chances of them marking your emails as spam.

5) Email Engagement 

Email engagement, or how recipients interact with your emails, directly impacts inbox placement.

Mailbox providers use recipient engagement metrics as a key indicator of a sender's reputation. High open rates, click-through rates, and replies signal that recipients find your emails valuable and relevant. This builds trust with mailbox providers and increases your chances of landing in inboxes for future campaigns.

Conversely, low engagement rates (low opens, clicks, high bounces) suggest recipients aren't interested in your content. This can hurt your sender reputation and lead to future emails landing in spam folders.

6) Email Content And Design 

Using ALL CAPS or spammy phrases like "free!", "limited time offer!", etc., can trigger spam filters and hurt your deliverability.

You should also not mislead recipients with misleading subject lines or false promises within the email content. 

Ensure your content is relevant to the recipient's interests. Similarly, while visuals can be engaging, too many images can increase email size and slow loading times. 

Poorly coded HTML or broken layouts can raise red flags for spam filters. 

7) Mobile Optimization 

Mailbox providers prioritize user experience, and if your emails render poorly or are difficult to interact with on mobile, it can negatively impact how they view your content. Some mailbox providers have additional spam filters specifically for mobile devices. These filters might look for elements that make the email experience clunky on mobile, such as:

• Excessive use of small fonts
• Buttons or links that are too close together and difficult to tap on a touchscreen
• Text that wraps poorly on smaller screens

Just like overall engagement, how recipients interact with your emails on mobile devices can influence inbox placement.

How To Improve Your Inbox Placement Rate?

Inbox placement is difficult to tackle. But the good news is that it is not impossible to achieve a good inbox placement rate. 

With a few tips and strategies (focusing strongly on the factors we discussed in the previous section), you can increase your inbox placement rate. 

Let’s look at these tips below: 

1) Always Use a Clean List 

A clean list means you're sending emails to valid and active addresses. This reduces the number of bounces, which occur when an email cannot be delivered due to an invalid address. High bounce rates can negatively impact your sender reputation and lead to emails landing in spam folders.

Spam traps are email addresses specifically set up to catch spammers. Accidentally sending emails to spam traps can significantly damage your sender's reputation. Regularly cleaning your list helps ensure you're not sending to these traps.

Email verification tools help identify invalid, disposable, or outdated email addresses on your list. These can lead to bounces, which occur when an email cannot be delivered. High bounce rates can negatively impact your sender reputation and lead to emails landing in spam folders.

You must also segment your lead list. Segmentation allows you to send emails that are highly relevant to specific groups of subscribers within your list. This relevancy is a crucial factor for mailbox providers. Here’s how you can segment your lead lists. 

If you’re using Smartlead for sending your emails, you can easily create lead lists with our integration with Clay.

2) Authenticate Your Email Account 

Authentication protocols like SPF, DKIM, and DMARC play a vital role in improving your inbox placement rate by verifying your identity as a legitimate sender.

When you implement these protocols, mailbox providers (like Gmail, Outlook) can easily confirm that the email actually originated from your domain and hasn't been spoofed by someone else. 

Check out our guide to efficiently set up SPF/DKIM and DMARC. 

3) Send Emails At a Consistent Frequency 

Sending emails at a consistent frequency can have a positive impact on your inbox placement rate in several ways.

Consistent sending habits, even if not super frequent, establish you as a reliable sender with valuable content. Mailbox providers track sending patterns, and consistent frequency shows you're not a random spammer sending out a blast every now and then.

Regular emails help your brand stay at the top of recipients' minds. If they know what to expect in terms of frequency, they're more likely to anticipate and open your emails when they arrive.

4) Avoid Spammy Language In Content or The Subject Lines

Mailbox providers like Gmail and Outlook use sophisticated spam filters to identify and block unwanted emails. These filters look for specific keywords, phrases, and formatting techniques commonly used by spammers. By avoiding these elements, you significantly reduce the chances of your emails getting flagged as spam and landing in the spam folder.

Spammy language can also be a major turn-off for recipients. Clear, concise, and informative subject lines that accurately reflect your email content are more likely to be opened. Recipients who find your content valuable and relevant are less likely to unsubscribe from your list.

How Spam Filters Identify Spammy Language:

Here are some common red flags for spam filters to look out for:

• Excessive Exclamation Points and All Caps: These tactics scream "trying too hard" and are a common giveaway of spam.
• Urgent or Pushy Language: Phrases like "Limited Time Offer!" or "Act Now!" can trigger spam filters as they create a sense of urgency often used in spam emails.
• Misleading or Deceptive Subject Lines: Subject lines that don't accurately reflect the email content can be misleading and get flagged as spam.
• Excessive Use of Spam Trigger Words: Certain words and phrases are heavily associated with spam. These can include "free!", "work from home!", "get rich quick!" etc.

Read more on why emails land in spam and how you can fix that. 

5) Resolve Bounces and Errors 

There are two main categories of delivery failures: bounces and errors.

Bounces: These occur when an email cannot be delivered due to an invalid address. Bounces can be temporary (mailbox full) or permanent (address doesn't exist).

Errors: These happen due to server-side issues on either the sender's or recipient's end. They can be temporary or permanent.

Your email marketing platform will typically provide you with bounce and error reports. These reports will detail the specific error code and the email address associated with the failure.

Taking Action on Bounces:

• Temporary Bounces: For temporary bounces (soft bounces), you can attempt to resend the email a few times after a waiting period.
• Permanent Bounces (Hard Bounces): For permanent bounces (hard bounces), remove the email address from your list. These addresses are invalid and will continue to cause bounces.

Here are some common bounce and error codes you might encounter, along with their meanings. 

6) Use an Email Deliverability Tool 

Email deliverability tools can be a valuable asset in your email marketing arsenal, helping you improve inbox placement rates in several ways.

These tools provide comprehensive insights into your email deliverability metrics. They track factors like bounce rates, spam trap hits, complaint rates, and overall sender reputation. This data helps you identify areas for improvement and optimize your sending practices.

7) A/B Test Your Emails 

A/B testing your emails is a powerful technique that can significantly improve your inbox placement rates by optimizing elements that influence open rates. 

A/B testing involves sending two or more variations of an email campaign to a small segment of your list. These variations differ in one specific element, such as the subject line, preheader text, or call to action (CTA) button. You then track which version performs better in terms of metrics like open rates, click-through rates, and unsubscribes.

While A/B testing doesn't directly impact inbox placement, it helps you optimize elements that mailbox providers consider when deciding where to deliver your emails. Elements to Consider for A/B Testing:

• Subject Lines: Test different subject lines to see which ones grab attention and encourage opens.
• Preheader Text: The preheader text is a short snippet displayed next to the subject line. A/B tests different preheaders to see which ones pique recipient interest.
• Call to Action (CTA) Buttons: Test different CTA button designs, text, and placement to see which ones drive more clicks.
• Email Content Formatting: Experiment with different content formatting, such as image placement and text layout, to see what resonates best with your audience.

How To Conduct An Inbox Placement Test In 5 Simple Steps 

1. Create Your Email Campaign

Choose a reliable email-sending tool like Smartlead or another service you are familiar with.

Begin by drafting the content of your email. This includes:

• Subject Line: Craft a compelling and relevant subject line that encourages recipients to open the email. Avoid using words that might trigger spam filters, such as "Free," "Discount," or "Buy Now." Here’re 80 subject line ideas for you. 
• Body Content: Write clear, engaging content that provides value to the reader. Use a conversational tone, short paragraphs, and bullet points for readability. Personalize the email where possible to increase engagement.
• Links and Images: Include relevant links and images that support your message. Make sure all links work correctly, and images load properly. Use alt text for images in case they don’t load.
• Call to Action (CTA): Ensure there is a clear CTA, guiding the recipient on what to do next, such as "Read More," "Shop Now," or "Sign Up."

Ensure your email-sending tool is properly set up with your email account and all necessary settings (sender name, reply-to address, etc.) are configured.

If you want more details on how to set up an email campaign in Smartlead, you should check out this guide. 

2. Create a Seed List

A seed list is a collection of test email addresses from various ESPs (Email Service Providers) like Gmail, Yahoo, Outlook, etc. These addresses are used to gauge how your email will perform across different platforms. Use your email testing tool to generate or provide a seed list. Many tools like GlockApps or others offer pre-compiled seed lists.

Add the seed list to your email sending tool by creating a new mailing list specifically for testing. Schedule the test email to be sent at the same time you plan to send your actual campaign. This helps in simulating real-world conditions.

Ensure that tracking for open rates, click rates, and other engagement metrics is enabled in your email sending tool.

3. Choose an Email Deliverability Test Tool

Here’s a list of top deliverability test tools

• GlockApps: Comprehensive tool for testing email placement, spam score, and authentication.
• Allegrow: Offers deliverability testing and real-time monitoring.
• MailGenius: Analyzes email content and provides suggestions to avoid spam filters.
• Inbox Inspector: Helps test deliverability across various ESPs and provides detailed reports.
• MailTester: Simple tool for checking spam score and email deliverability issues.

4. Analyze the Report

Access the initial placement results from your chosen testing tool to see where your emails landed (inbox, spam folder, or blocked).

Review detailed reports to identify which ESPs delivered your email to the inbox and which sent it to the spam folder.

Examine the reasons provided by the tool for emails landing in the spam folder. Common reasons include:

• Content Issues: Use of spammy words or poor-quality content.
• Authentication Failures: Issues with SPF, DKIM, or DMARC records.
• Spam Score: High spam score due to various factors.

5. Improve Your Emails

Make necessary changes to avoid spammy words and phrases. Ensure your HTML is clean and optimized. Ensure your email is responsive and looks good on mobile devices.

Regularly monitor and manage your sender reputation. Avoid sending emails to invalid addresses, which can increase bounce rates and harm your reputation. Keep track of bounced emails and remove invalid addresses from your list.

Conduct multiple rounds of testing after making improvements to ensure that your changes have positively impacted email deliverability. Continue to tweak and test until you achieve the desired results.

Winding-Up

By understanding inbox placement rates and utilizing email deliverability testing, you can gain valuable insights into how email providers perceive your messages. This knowledge empowers you to optimize your email campaigns, land more emails in inboxes, and ultimately, achieve your marketing goals. Take control of your email deliverability and watch your engagement rates soar!

FAQs 

1. What's the difference between inbox placement rate and delivery rate?

Delivery rate refers to the percentage of emails that were successfully delivered to the recipient's server, regardless of where they end up (inbox, spam folder, etc.). Inbox placement rate, on the other hand, specifically focuses on the percentage of emails that land in the recipient's primary inbox. While a high delivery rate is important, a strong inbox placement rate is crucial for getting your message seen.

2. What's a good inbox placement rate to aim for?

There's no single "magic number" for a good inbox placement rate, as it can vary depending on your industry and the email service providers (ESPs) used by your recipients. However, generally, a rate above 80% is considered excellent, 70-80% is good, and anything below 70% indicates room for improvement.

3. Do I need a special tool to check my inbox placement rate?

Yes, while some email marketing platforms offer basic deliverability insights, dedicated email deliverability testing tools provide more comprehensive reports. These tools utilize seed lists containing email addresses from various ESPs to analyze where your emails land (inbox, spam, etc.). This allows you to identify areas for improvement and optimize your campaigns for better inbox placement.

4. Do I need to do multiple inbox placement tests?

Inbox placement testing isn't a one-time thing. Email providers and your own campaigns evolve, so regular testing helps you stay on top of deliverability best practices, optimize for different email service providers your audience uses, and verify the effectiveness of changes you make to improve inbox placement rates.