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What is Spam Score and how is it calculated ?

damien ceo mailreach
David Chastanet
Email Deliverability Expert

In this guide, we will delve into the intricacies of Spam Score, exploring its calculation methodology and also its impact on your email deliverability. By the end, you will have a clear understanding of how Spam Score influences your email outreach efforts. Let’s go !

What is Spam Score and how is it calculated ?

If you have ever experienced the frustration of sending emails that never seem to reach their intended recipients, you need to learn a few more things about the Spam Score and how it is calculated. Your Spam Score can make a significant difference in your email delivery rates. Similar to DMARC, which ensures secure email delivery, grasping the essence of Spam Score empowers you to optimize your email campaigns for a better inbox placement.

In this guide, we will delve into the intricacies of Spam Score, exploring its calculation methodology and also its impact on your email deliverability. By the end, you will have a clear understanding of how Spam Score influences your email outreach efforts. Let’s go !

What is Spam Score ?

Spam Score can be described as a grade given to your email to predict its likelihood of ending up in the spam folder instead of the recipient's inbox. It is a measure of your email deliverability

Here's how it works : imagine sending out a test email to a set number of email accounts, and then calculating how many of those emails actually make it to the main inbox. This ratio of delivered emails to total emails sent is then converted into a score, typically ranging from 0 to 10. 

The higher the score, the better the chance your email has of bypassing spam filters and landing where it is intended. 

How are Spam Scores calculated ?

The calculation of Spam Scores follows a specific formula, such as the one used in MailReach's spam test. This formula typically involves dividing the number of emails successfully delivered to the inbox by the total number of emails sent, then multiplying the result by 10. 

For instance, if you send a test email to 30 mailboxes and it lands in the inbox of 20 recipients, the calculation would be 20/30*10, resulting in a Spam Score of 6.6 out of 10.

You must keep in mind that obtaining an accurate Spam Score requires conducting a genuine deliverability test by sending emails to a sufficient number of mailboxes. This ensures that the score is based on real-world deliverability performance

What is a good Spam Score ?

A good Spam Score is directly linked to your email deliverability, because it assesses the likelihood of an email being flagged as spam by email service providers' spam filters. 

A high Spam Score indicates that the email shares characteristics with spam emails and is therefore more likely to be blocked or filtered by mail servers before reaching the recipient's inbox. 

On the other hand, a low Spam Score suggests that the email is more likely to be successfully delivered to the recipient's inbox, increasing the chances of the recipient seeing and opening it. 

However, a high Spam Score doesn't necessarily mean the site is spammy. Instead, it suggests the need for further investigation regarding the quality and the relevance of the site. This underscores the importance of interpreting Spam Scores in context and utilizing them as a tool for assessing website credibility and reliability.

Tools for checking Spam Score

When it comes to online platforms for spam scoring, there are several options available, each with its own advantages and limitations. Let's take a closer look at three prominent platforms : MailReach Spam Test, GlockApps and Gmass

Mailreach's Free Email Spam Test and Checker

Mailreach's Free Email Spam Test and Checker offers a free, helpful, and reliable solution that aims to provide accurate insights into email deliverability. Unlike some other tools, MailReach's Spam Test is designed to be unbiased and genuinely useful.

By sending your email to a list of 31 inboxes, including major providers like Gmail, Google Workspace, Outlook, Office 365, and Yahoo, you can get a comprehensive overview of your inbox placement. The tool analyzes your content, sending setup, and provides a score out of 10 based on where your email lands. This approach helps you to identify potential issues and offers actionable recommendations for improvement.

Pros : 

✅ Reliable and not biased

✅ Gives a score according to the type of mailboxes you target

✅ Significant number of inboxes : good accuracy

✅ Relevant and helpful checks and insights to help you improve

✅ User friendly


Cons : 

❌ Doesn’t test towards local and very specific mailbox providers. MailReach focuses on the major ones : Google Workspace, Gmail, Office365, Outlook, Hotmail, Yahoo, etc.


GlockApps is another popular option for testing inbox delivery and spam filtering. While it offers a wide range of testing options across various inbox providers, users should be cautious as some features may require payment

Similar to MailReach’s Spam Test, GlockApps provides detailed reports on inbox placement, content analysis and actionable steps to enhance deliverability. However, the size of the inbox list may vary depending on the selected categories, such as Popular US, Business US, Canada, Europe, and others.

Pros :

✅ Reliable testing method : directly send your email to a seed list

✅ Good variety of local and specific mailboxes : country, type..

✅ Automatic tests


Cons : 

❌ Only one G Suite (B2B) tested compared to 12+ inboxes (B2C). That means a limited accuracy to test your email deliverability on professional inboxes.

❌ Only one Exchange / Office365 (B2B) tested compared to 12 inboxes (B2C). That means a limited accuracy to test your email deliverability on professional inboxes.

❌ No ability to adapt your report based on the type of inboxes you target (B2B vs B2C) as spam filtering is different between the two AND it’s normal to land in spam when sending professional content to personal inboxes.

Gmass Deliverability Tester

On the other hand, Gmass Deliverability Tester offers a free and straightforward solution, but with some limitations. Designed primarily as a Chrome extension for email automation, Gmass allows users to test their inbox placement in Google inboxes. 

While it lacks the comprehensive analysis provided by other tools, it can still be useful for quickly checking where your email lands among 15 Google inboxes.

Pros : 

✅ Simple and easy to run. Minimum friction

✅ Quick result

Cons : 

❌ You can only test your deliverability towards Google inboxes. There’s no other mailbox providers. That’s half of the market.

❌ There’s no report to analyze your email and give you insights to improve your email deliverability.

❌ The results disappear after several hours, you can’t keep track of your deliverability tests and follow your progress.

Spam Score : monitoring and adjusting your strategy

Regularly monitoring your spam scores and understanding the results is essential to optimize your email marketing strategy. By keeping an eye on your spam scores, you can gain valuable insights regarding how your emails are being perceived by spam filters and recipients' mailboxes. This allows you to identify any potential issues or patterns that may be affecting your email deliverability.

Once you have a clear understanding of your spam scores, you can then adapt your email marketing strategies accordingly. This may involve making adjustments to your email content, sender reputation, authentication protocols or the mail tester alternatives used to improve your deliverability rates. 

10 tips to maintain a healthy Spam Score

Here's a breakdown of 10 tips to maintain a healthy Spam Score : 

Tip #1 : Set up your SPF, DKIM and DMARC

SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) are three key technologies that help protect email senders and recipients from spam, phishing, and other malicious email activities. 

SPF allows email senders to define which IP addresses are allowed to send emails on their behalf, helping to prevent impersonators. 

DKIM provides a digital signature that verifies that an email was indeed sent from the domain it claims to be from and that its content hasn't been tampered with during transit.

DMARC builds on SPF and DKIM by allowing domain owners to specify how email receivers should treat emails that fail SPF or DKIM checks. 

It also provides a way for receivers to report back to senders about emails that pass or fail these checks. 

Together, SPF, DKIM, and DMARC form a trio of defenses that make it harder for attackers to misuse email, ensuring that only authorized senders can send emails from a domain and that the content of these emails remains unchanged from sender to receiver.

Here's how to properly set up SPF and DKIM records

Tip #2 : Send your emails from reputable email providers

For cold outreach, the 3 providers with the highest deliverability are Google Workspace, Office 365 (Exchange), and Zoho.

For opt-in, newsletters, transactional emails: Brevo offer the highest deliverability. 

These providers consistently demonstrate higher deliverability rates compared to others in the market. Given that Google, Microsoft and Zoho dominate the mailbox industry, there is no surprise in the fact that emails sent from their platforms have better chances of reaching recipients' inboxes, so choosing one of these top three providers can significantly enhance your email deliverability. 

Once you have selected your preferred provider, you can seamlessly integrate it with an outreach solution to automate your email sequences directly from your inbox.

Tip #3 : Never send more than 100 cold emails per day per inbox

When engaging in cold outreach, it is essential to limit the number of cold emails you send to avoid being flagged as spam. Our recommendation is to refrain from sending more than 100 cold emails per day per email address, and ideally per email domain. 

Remember, the key is to mimic human behavior. Think about it : no individual realistically sends thousands of marketing emails daily. By conducting various tests, we have found that sending fewer emails per day significantly improves your sender reputation and overall your email deliverability.

These guidelines apply specifically to your genuine outreach emails and do not include any warming emails. If you find yourself needing to send a higher volume of emails, consider the following strategies : diversify your domain names (refer to Tip #1), create a separate email address for each domain, and maintain positive engagement on each address through consistent warming activities.

Tip #4 : Use email warm up to maximize your engagement rate and maintain a high sender reputation

Many individuals believe that email warm-up is only necessary before launching email campaigns. However, performing a one-time warm-up prior to sending emails is not sufficient to maintain excellent deliverability and a strong sender reputation over the long term. Consistent warm-up activities are essential both before and during your campaigns to ensure optimal results. 

Achieving a high engagement rate, characterized by positive interactions such as email opens, clicks and replies, is a « must have » in order to build a positive sender reputation and avoid the spam folder. If recipients are actively engaging with your emails, it indicates that your content is valuable and relevant to them. Without continuous email warming efforts, relying solely on enticing offers, captivating subject lines and universally appealing email content to generate positive engagement becomes challenging.

When sending email campaigns, some of your emails may inevitably be flagged as spam. Each instance of your emails being marked as spam can significantly harm your sender reputation and deliverability. This realization led us to develop MailReach after years of experience in sending cold email campaigns and addressing deliverability and reputation issues. 

As a bonus : our platform optimizes your email content to navigate through spam filters effectively, thanks to its powerful spam checker tool.

Tip #5 : Regularly test your email deliverability and inbox placement with our free spam test

In order to regularly assess your email deliverability, you can use MailReach's Free Email Spam Test to determine your spam score and the placement of your emails. Unlike many other spam checkers that may be biased or unreliable in accurately gauging your inbox placement, MailReach offers a trustworthy solution.

The process is straightforward: 

  • send an email under your actual sending conditions to a predefined list of 31 inboxes provided by MailReach ;
  • you will receive a comprehensive report detailing your email deliverability, along with actionable insights to enhance your inbox placement ;
  • this report includes a score ranging from 1 to 10, as well as a checklist covering various aspects such as content analysis, identification of spam words, assessment of links, tracking mechanisms, blacklist status, and more.

Tip #6 : Minimize the number of links in your emails

The fewer links in your email, the better for your spam score. 

If you really need to send a link, make sure the website is https secured (to check it, open the website in Chrome and check if you can see the little padlock on the left of the URL). 

There are many links associated to spam. We've seen tons of time people land in the spam folder just because of one link in their content, beware.

Tip #7 : Make sure to use a custom tracking domain

When you send out email campaigns or sequences and are able to track the opening and click rates, it means your emails have tracking elements like pixels or URLs embedded in them. These trackers, typically included by default in emails sent via automation tools, let you monitor the performance of your campaigns by providing insights into how many people are opening your emails and clicking on links within them.

However, a common issue arises when the tracking domain used in your emails is the default one provided by the email automation tool, shared among all its users. This means your emails are linked to the same domain as many other users, including potential spammers. If these users engage in behavior that gets the domain flagged as spam, your emails could be negatively affected, potentially harming your reputation and deliverability.

To avoid this, it's crucial to set up a custom tracking domain for your email campaigns. This not only isolates you from the potential negative actions of others using the same email automation tool but also helps in building and maintaining your own sending reputation. 

Most email automation services offer the option to set up a custom tracking domain, which should ideally be the same as your sending email address domain. Ensuring your email communications have a consistent domain enhances credibility and helps in avoiding the spam folder.

Tip #8 : Use some basic personalization in your emails

Incorporating basic personalization into your emails can significantly improve your campaign outcomes, including open rate, click rate, reply rate and lead rate. Moreover, personalization plays an important role in enhancing your email reputation and deliverability.

When you personalize your emails, you avoid sending the same generic message to every recipient. This demonstrates to email service providers like Google and Microsoft that you have some knowledge about your recipients and are not simply mass-emailing indiscriminately.

Our main advice : always strive to communicate in a human-like manner. Real individuals do not typically send identical emails to thousands of people each day. When we talk about personalizing email authentication, we are referring to using the recipient's name (first name and/or last name) and, if possible, their company name.

Tip #9 : Avoid triggering Spam Words

When crafting your emails, you must avoid using words or phrases that might trigger spam filters. These are not always the obvious ones like "viagra" or explicit content. For example, if spammers suddenly start using a term like "Crypto" in their mass emails, it could become flagged as spam by algorithms due to user reports.

Be also mindful of other elements that can raise red flags for spam filters, such as aggressive punctuation like excessive exclamation marks (!!!), excessive capitalization, or attachments, which are often associated with phishing attempts. Limit the number of links in your email, ensuring they lead to secure HTTPS websites, as links can also contribute to emails being marked as spam.

Moreover, be cautious with image-heavy content and excessive HTML formatting in your emails. Too many images or complex HTML code can negatively impact your email deliverability. Remember, emails should be formatted in a way that mimics human communication, with minimal formatting and a focus on clear, concise content.

To ensure your emails pass through spam filters successfully, do not hesitate to use an email spam test tool. This tool allows you to assess your email deliverability by testing how your emails perform across various inboxes. By identifying potential issues and making necessary adjustments, you can increase the chances of your emails landing in recipients' inboxes rather than their spam folders.

Tip #10 : Include an easy-to-spot unsubscribe link

If you include an easy-to-find unsubscribe link in your marketing emails, you will be able to protect your sender reputation and maintain compliance with regulations like GDPR and CAN-SPAM. This link gives recipients the option to opt out of receiving further emails from you, demonstrating respect for their preferences and reducing the likelihood of them marking your emails as spam.

By making the unsubscribe link prominent and easy to locate, you empower recipients to manage their email preferences effortlessly, fostering trust and goodwill. Moreover, providing a straightforward way to opt out can help prevent recipients from resorting to more drastic measures, such as reporting your emails as spam.

MailReach is compatible with any inbox / SMTP

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