How to Calculate Inbox Placement Rate (+6 Ways to Boost It)

Inbox Placement Rate (IPR) is an email marketing KPI that measures how many emails are delivered to a recipient’s primary inbox instead of their spam folder.  

In this article, we’ll cover how to calculate your inbox placement rate and 6 ways to boost it. 

We’ll also introduce you to an email deliverability tool that can seriously improve your inbox placement.

This Article Contains

• How to Calculate Inbox Placement Rate?
• 6 Best Practices to Improve Your Inbox Placement Rate

Let’s get started.

How to Calculate Inbox Placement Rate?

Subtract the number of emails that end up in the spam or junk from the total emails delivered. Then, divide that number by the number of emails delivered. 

Then, multiply that figure by 100.

Here’s the formula:
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Here’s an example, let’s say you send 100 emails, and 93 of them get delivered. 

Now, 10 of them end up in the junk or spam folder, while the rest land in your recipients inbox. 

In this case, your inbox placement rate is 89%.

Some users confuse the email deliverability rate with the inbox rate. Just because an email message doesn’t bounce (and you have a low email bounce rate) doesn’t mean it'll correctly land in the primary inbox. 

The number of emails that didn’t bounce is your email deliverability rate – not your inbox placement rate. (‘Emails delivered’ is worked out by subtracting bounces from the total number of emails sent).

Your email deliverability will include emails landing in other folders like Promotions, Unfocused, or even the Junk or Spam folder, where they remain unopened. 

Your inbox rate ONLY includes emails that end up in your recipient’s primary inbox.

Confused about how to analyse your inbox placement rates?

Read our guide on how to monitor and boost the placement rate of your emails.

6 Best Practices to Improve Your Inbox Placement Rate

Here are six ways you can boost your inbox rate:

1. Build a Relevant Recipient List & Authenticate Sending

Building a focused email list that actually engages with your content is a surefire way to boost inbox placement rates. 

But how do you get prospects in your email list to engage with your content in the first place?

Most prospects question the significance of an outbound email message that lands in their inbox. They often ask themselves: “Is this relevant for me?”

You can address this initial concern at the outset with hyper-relevance or a trigger explanation for the cold email message. 

Hyper relevance doesn’t mean using just the prospect's industry or job title to attract them. 

Instead, customize your email marketing campaign based on different data sources like: 

• The content your prospect engaged with on Linkedin/Twitter 
• The reviews left by the company’s employees on Glassdoor
• Any changes in your prospect’s current tech stack, and so on

Using such specific triggers in your opening lines proves you’ve done your homework and aren’t shooting generic spam content at your prospects. 

Additionally, ensure you set up proper email verification protocols like DKIM (DomainKeys Identified Mail), SPF (Sender Policy Framework), and DMARC (Domain-based Message Authentication, Reporting & Conformance). 

Without these protocols, your messages will likely end up in the spam folder.

2. Send Emails at the Right Frequency  

While sending engaging content is essential, too much volume too fast can hurt your email deliverability. 

Instead, opt for throttled sending. 

Throttling is when you gradually send emails from your domain instead of bulk sending. This increase seems more natural to your email provider and increases your inbox placement and email delivery rate. 

Also, while conducting email marketing, consider limiting the number of messages you send from each inbox. Sending out hundreds of daily emails can look very spammy and affect your email deliverability. 

How many outbound emails you should send out can vary depending on your situation. 

For instance, sending around 80 emails from an existing mailbox & domain would be safe. However, for a new mailbox, even on an existing domain, 80 sent emails daily would alert your internet service provider and likely affect your inbox placement and email delivery rate.

Here’s our guidance on mailbox sending limits to help your IP address avoid the spam trap:

3. Use Optimized, Non-Spammy Subject Lines

Did you know that certain words in your subject line can increase the likelihood of a mailbox provider putting your sent emails in a spam folder?

In email marketing, subject lines greatly influence your inbox placement and open rate. In fact, 35% of recipients decide whether to open your delivered emails based solely on the subject line! 

While it may be tempting to sell your content in the cold email and be too expressive in the subject line, it’s better to keep things boring. 

Spammy subject lines tend to turn off most prospects and can even send your delivered emails to the junk folder for resembling generic messages with low engagement.   

Here’s an example of what NOT to use to boost your open rate:

Trouble acquiring qualified leads, {{FirstName}}?

If you don’t want an email service provider to send your emails to a spam folder, your subject lines need to be relevant and concise.

Some best practices to avoid the spam trap could be to use:

• Three words or less
• Title case
• No punctuation
• Plain words over complicated vocabulary
• A subject line that reflects your email content 

This way, your email provider won’t mark your messages as spam, and every email prospect will know what to expect. Your inbox placement rate, email deliverability, and open rate will also improve. 

Interested in learning more? Check out our article on why inbox placement is important for your business.

4. Segment Your Email List with an Optimal ABM Approach

A spam filter can quickly identify irrelevant, generic, and spammy emails that originate in bulk from one domain. 

How do you sidestep these filters while email marketing?

With account-based marketing (ABM), you can approach the best-fit accounts in your list without landing in the spam folder.

This involves spacing out the point at which different email addresses at the same account are approached and sent follow-up emails. 

For instance, to overcome spam traps, you could segment your email marketing contacts based on parameters like:

• Active Contacts: Number of email addresses you can message within 30 days. 

• Minimum Spacing: The minimum time lapse between sending an email to a different contact at the same account. 

• Unenrollment Trigger: The trigger to remove a specific contact from your sales email cadence due to their inactivity/unresponsiveness.

Here’s a look at some parameters an email marketer should set for various business sizes to counter spam traps:

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5. Test Your Emails Before Sending

Think every email will deliver brilliant results?

Think again.

Just because your previous email marketing campaign performed well doesn’t mean your next one will.

One way to optimize your email campaigns for inbox placement and avoid spam complaints is to send different variations of your message to email addresses. 

This process is known as content testing, and it can help any email marketer determine how well each email variation does in landing in a recipient’s primary inbox. 

Use this data to learn how to present your value proposition better so that your outgoing email campaigns land in the primary recipient’s inbox and don’t result in a spam complaint. 

To avoid content getting stale, you should update the templates of email campaigns you use at least once every 60 days. Examples of the aspects you can edit in your email campaign are as follows:

• Subject Lines (number of words/keywords used)
• The volume of words in the entire email (replies tend to spike at the 50-word mark for a cold email)
• Links used (volume of links, types of links)
• Call to action (asking for something different in your email campaign that can yield significantly different results)
• Signature / Footer details. (even consider testing differences in the sender name/profile as well as these details)

You can also send a sample of your newly created content to specific mailbox communities through tools like Allegrow. These inbox tracker features identify which folder the content lands in and compare it against your current version before you send a live email campaign to real prospects.   

6. Leverage Technology like Allegrow

While you can try all the tips we’ve mentioned to boost your email deliverability and inbox placement rate — it may not be enough.

There are billions of emails sent out daily, and you need an high sender reputation to land in the recipient’s primary inbox every time you launch an email marketing campaign. 

That’s where an email deliverability tool like Allegrow comes in.

Allegrow is a platform that measures the percentage of your emails that land in the spam folder vs. the primary inbox each day — based on data from actual B2B inboxes. 

Combine this with Allegrow’s functionality to help you incrementally improve inbox placement over time — and you have a single source of truth for inbox placement. 

Here’s how Allegrow does it:

• Sends emails each day to actual B2B inboxes inside the Allegrow network
• Measures exactly where your emails land - creating a reliable data point for sender reputation or calculating the sender score
• Increase positive interactions on your domain (including replies and emails being marked as important and moved out of spam)
• Allows you to test different variations of your content and see which versions land in spam more or less often (so your content doesn’t get caught in filters)
• Provides insights based on data from thousands of live spam folders, helping you optimize your sender reputation (sender score) 
• Allows you to compare the sender reputation and health scores of different reps across your go-to-market team
• Works hand-in-hand with your sales engagement system while integrating directly into your mailboxes 

Sign up for Allegrow today to measure and improve your inbox placement rate!

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