How to measure email deliverability? List of the essential metrics to follow (2025)

‍Measuring email deliverability is all about knowing which metrics matter. It’s all about tracking the data that shows if your emails actually hit the inbox. No worries, you will precisely find the key metrics that you need to follow in 2025 to keep your campaigns on track. Straight answers, no fluff: just what you need to make sure your emails get seen! 

What is email deliverability?

Email deliverability is the ability of your emails to land in your recipients' inboxes, not in their spam folders. Unlike email delivery, which just tracks if the email reached the server, deliverability focuses on where it actually ends up. 

What does it mean? Simply that if your deliverability isn’t spot-on, you’re losing money, plain and simple. Emails in spam mean missed customers and missed sales opportunities. So to make sure your emails convert, they have to reach the inbox. No excuses.

Email deliverability is based on 3 factors

A great sender reputation

Your sender reputation is the score that email providers use to judge if your emails are worth delivering. It’s built on your engagement rate: the more opens, clicks, replies, and positive interactions you get, the stronger your reputation. 

Things like minimizing spam complaints, having your emails marked as important, or pulled out of the spam folder: all boost your sender score. High reputation equals better deliverability. 

As a result, if your engagement drops, so does your chance of reaching the inbox. Our tip: focus on earning those positive signals to keep your reputation solid and your emails seen. Always. 

To get more details, you can also reed: 7 ways to Improve Email Sender Reputation in 2025

Sending email content free of spammy elements

Even with a great sender reputation, your emails can still get flagged as spam if your content raises red flags. It’s sad, but it’s true.

Links, excessive tracking codes, too many images, or even your email signature can all trigger spam filters. Why? Because spam filters analyze every element of your email, looking for patterns that scream "junk." 

If your content looks too promotional or has too many spammy elements, it won't matter how good your reputation is: you’ll still end up in the spam folder. 

Knowing that, keep your content clean, balanced, and relevant to make sure it actually reaches your audience. The key: anticipation!

Using the right sending setup

Your sending setup plays a massive role in email deliverability. If you’re not using the right email service provider (ESP) or haven't properly authenticated your emails with SPF, DKIM, and DMARC, you're almost guaranteed to land in spam. Why? Because not all ESPs are created equal: some get your emails into inboxes far more reliably than others.

Here are some tips: 

• For B2B cold outreach, go with Google Workspace or Office365. They’re proven to get your messages into inboxes more consistently;
• For B2C campaigns, opt-ins, or newsletters, tools like Brevo and Mailchimp are your best bet. They’re optimized for high deliverability and built to handle large-scale campaigns. 

Keep in mind that even if the right setup isn’t optional, it’s the key to making sure your emails get seen and don’t end up as digital trash.

How to measure email deliverability

The only reliable way to measure email deliverability is to run a spam test (inbox placement test) that mirrors the exact conditions of your actual campaigns. You need to see where your emails land: inbox, spam, or promotions tab. Why? Because it will give you a clear picture of how many of your emails actually reach the inbox.

Running a spam test under the same conditions as your actual campaigns is extremely important. It simulates the real sending environment, so you can see exactly how email providers are handling your messages. 

The MailReach Spam Test is your go-to tool for this: it’s designed to give you the most accurate picture of your inbox placement and also of your Spam Score. So thanks to our tool, you will learn about where your emails are ending up, potential issues, and what to fix to boost your deliverability. All of that, with one single Spam Test. 

It’s the fastest way to diagnose problems and fine-tune your strategy for maximum impact. Don’t leave it to chance: test, analyze, and adjust!

Check your Spam Score right away

How to maximize email deliverability

Maximizing email deliverability starts with getting your sender reputation in shape. It’s as simple as that.

For B2B cold outreach, email warmup is a must, as it gradually builds your sender reputation by generating engagement through opens, clicks, and replies. This process strengthens your reputation, yes, but also lets you track it in real-time, which is a huge benefit. 

With MailReach, you get a Reputation Score that shows exactly how your sender reputation is performing, giving you control over your campaign’s success.

But that’s just the beginning. To keep your emails out of spam and landing in inboxes, you need to run regular spam tests (inbox placement tests). We said: regular! These tests let you see where your emails are ending up (inbox, spam, or promotions tab), so you can measure your deliverability and make quick adjustments before it impacts your results.

Good news: MailReach offers both email warmup and spam test services designed to take the guesswork out of email deliverability. Our tools will help you optimize your campaigns and ensure your messages reach their target audience. 

Make sure you’re always one step ahead: optimize your deliverability strategy with MailReach and get your emails where they belong. And that’s it.

Discover the best email warmup tool for a perfect deliverability