What is SpamAssassin Score? How to Fix It In 2025?

The SpamAssassin score plays a crucial role in determining whether your emails land in the inbox or the spam folder.

It works like a two-way sword by helping email users stay out of spammy emails but punishing the cold emailers by flagging their emails as SPAM.

If your score is too high, your emails may never reach your recipient, hurting your outreach and engagement. 

But how does SpamAssassin evaluate emails, and what can you do to keep your score low?

In this blog, we’ll break down how SpamAssassin works, what factors influence your spam score, and actionable steps to improve email deliverability. 

So let’s start with the basics. 

What is spamassassin?

SpamAssassin is an open-source email filtering system designed by Justin Mason and developed under the Apache Software Foundation to identify and block spam emails. . It uses a variety of techniques to analyze incoming emails and assign a spam score. 

The higher the score, the more likely the email is considered spam.

It works by applying rule-based tests, Bayesian filtering, blacklists, DNS filtering and machine learning algorithms to detect unwanted or malicious emails. 

In today’s world, many email service providers such as Gmail integrate SpamAssassin into their mail servers to improve email security and reduce spam clutter in users’ inboxes.

Since it is highly configurable, users can adjust the sensitivity of SpamAssassin by modifying the scoring threshold or adding custom rules to suit their needs.

How does SpamAssassin score work in email?

SpamAssassin scores emails by analyzing their content, headers, and metadata against a set of predefined rules and tests. 

Each rule assigns a numerical score, either positive or negative, based on how likely it is that the email is spam. 

The final SpamAssassin score is the sum of all individual rule scores.

The scoring process works by the following steps:

1. Header analysis 
2. Content filtering
3. Bayesian filtering 
4. Blacklist and whitelist checks 
5. Authentication verification
6. Heuristic rule matching 
7. Custom rule tests

Note: The steps are discussed in detail below.

Once all tests are performed, SpamAssassin assigns a final score. 

If the score exceeds a configurable threshold (usually set at 5.0 by default), the email is flagged as spam. Conversely, a lower score means the email is considered legitimate.

For example:

• Spam Email (Score: 7.5) ➤  An email containing excessive promotional phrases like “100% free money!”, multiple exclamation marks, and suspicious links may receive a high score and be marked as spam.

• Legit Email (Score: 2.3) ➤  A transactional email with a clear subject, authenticated sender, and no spammy content, such as an invoice or order confirmation, would score below the threshold and land in the inbox.

How does SpamAssassin affect email deliverability?

Understanding spamassassin’s impact helps businesses optimize their emails for higher deliverability.

Let’s understand it in detail: :

• If an email receives a high SpamAssassin score (typically above 5.0 by default), it is likely to be flagged as spam and sent to the recipient’s spam folder, reducing the chances of it being seen.

• Emails that score significantly high (e.g., 10+) may be rejected outright by the recipient’s mail server, preventing delivery altogether.

• Repeatedly triggering high SpamAssassin scores can harm a sender’s email reputation, leading to long-term deliverability issues and lower inbox placement rates.

• While legitimate senders aim to pass SpamAssassin filters, the system helps protect users by blocking phishing attempts, malware, and fraudulent emails.

• Different email providers and businesses set their own SpamAssassin thresholds, meaning an email that passes one filter might get flagged as spam by another.

What does negative SpamAssassin score mean?

A negative SpamAssassin score indicates that an email has strong characteristics of a legitimate message rather than spam. 

Since SpamAssassin assigns a cumulative score based on multiple tests, a negative score suggests that the email has passed key authentication checks and follows best practices for email deliverability.

Negative SpamAssassin score typically means:

• High trustworthiness where the email contains elements that SpamAssassin recognizes as indicators of a safe and legitimate message, such as proper formatting and authentication records.

• Passed authentication checks like SPF, DKIM, and DMARC.

• The email avoids excessive use of spam-related words, misleading subject lines, or aggressive sales tactics that usually contribute to high spam scores.

• Well-structured emails with appropriate HTML coding, a balanced text-to-image ratio, and a clear sender identity often receive lower or negative scores.

How does SpamAssassin work & what are the common tests?

SpamAssassin works by analyzing incoming emails using a scoring system that evaluates multiple factors to determine whether an email is spam or legitimate. 

It applies a series of tests and assigns positive or negative points based on the email’s characteristics. 

If the total score exceeds the predefined threshold (default is 5.0), the email is flagged as spam.

Here’s a detailed breakdown of how SpamAssassin works:

➥ Header & Metadata Analysis

SpamAssassin examines email headers to detect signs of spoofing, forged sender addresses, or suspicious routing. 

It checks:

• Sender domain → Whether the domain has a history of sending spam.
• Return path & email routing → Identifies inconsistencies in email transmission.
• Email subject & formatting → Looks for misleading subject lines or excessive capitalization.

Common test are:

• FORGED_HELO – Detects fake email headers that spoof sender identity.
• RCVD_IN_DNSBL – Checks if the sender’s IP is listed in spam blacklists.
• SUBJ_ALL_CAPS – Flags emails with subject lines written in all caps.

➥ Content Filtering

The body of the email is scanned for spam-like characteristics, such as:

• Spam trigger words → Terms like “free money” or “urgent offer.”
• Excessive use of links → Too many external links, especially shortened URLs.
• HTML obfuscation → Hidden text, invisible characters, or misleading formatting.

Common content filtering tests are:

• MIME_HTML_ONLY – Detects emails that contain only HTML without plain text.
• FREEMAIL_FROM – Flags emails sent from free email services (e.g., Gmail, Yahoo) when unexpected.
• LOTS_OF_MONEY – Identifies phrases related to financial scams (e.g., “You’ve won $10,000!”).

➥ Bayesian Filtering (Machine Learning)

SpamAssassin uses a Bayesian classifier to analyze words and phrases based on past emails. 

It compares:

• Words and patterns commonly found in spam vs. legitimate emails.
• The probability of an email being spam based on previously learned data.

Common bayesian tests are:

• BAYES_99 – Indicates a very high probability (99%) that the email is spam.
• BAYES_00 – Suggests the email is likely legitimate (0% chance of being spam).

​​➥ Blacklist & Whitelist Checks

SpamAssassin cross-references sender domains and IPs against:

• DNS-based Blacklists (DNSBLs) → Lists of known spam sources.
• Whitelists → Trusted domains that should bypass spam checks.

➥ Authentication Verification

To prevent spoofing and phishing, SpamAssassin checks:

• SPF (Sender Policy Framework) →Verifies if the sender is authorized to send emails from that domain.
• DKIM (DomainKeys Identified Mail) → Ensures the email has not been altered in transit.
• DMARC (Domain-based Message Authentication) → Confirms alignment between SPF, DKIM, and the “From” domain.

Common blacklist & authentication tests include:

• SPF_FAIL – Sender’s domain fails SPF authentication, indicating possible spoofing.
• DKIM_INVALID – DKIM signature is present but invalid, suggesting tampering.
• DMARC_POLICY_REJECT – DMARC policy rejects the email due to failed authentication

➥ Heuristic & Plugin-Based Rules

SpamAssassin uses a vast database of rules to detect spam behavior. 

Users can also integrate plugins for advanced filtering, including OCR-based image spam detection or third-party threat intelligence.

➥ Custom Rule Testing

SpamAssassin allows users to create custom rules to enhance spam detection based on their specific needs. 

These rules can be tailored to flag emails containing certain keywords, unusual sending patterns, or specific formatting styles.

For example:

• A company may add a rule to block emails containing specific phishing terms or suspicious attachments.
• An organization can whitelist internal email addresses to prevent false positives.

Custom rule testing gives users more control over spam filtering, ensuring better accuracy and adaptability for different business requirements.

#7 Tips for improving SpamAssassin score

Here’s how you can improve your SpamAssassin score and enhance email deliverability.

✅ Authenticate your emails

Email authentication is a critical factor in improving email deliverability. 

SpamAssassin checks whether your emails pass SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) authentication protocols. 

Setting up these records in your domain’s DNS helps verify that your emails come from a legitimate source. Failing authentication tests like SPF_FAIL or DKIM_INVALID can significantly increase your spam score. 

Additionally, regularly check if your domain or sending IP is listed on spam blacklists (DNSBLs), as this can negatively impact your email reputation.

✅ Use a recognizable sender name & email address

Emails from unknown or suspicious senders are more likely to be marked as spam. 

Instead of using free email services like Gmail, Yahoo, or Outlook, always send emails from a domain-based email address (e.g., [email protected]). 

This not only looks professional but also improves credibility. 

Additionally, avoid frequently changing sender names, as inconsistent sender identities may trigger spam filters.

✅ Optimize email content to avoid spam triggers

The content of your email plays a major role in determining its spam score. SpamAssassin assigns points for certain spam triggering words. 

Avoid using excessive promotional language, such as

•  “Congratulations! You’ve won!” or “Get rich fast!” 

Additionally, do not overuse words like 

• “free,” 
• “urgent,” 
• “guaranteed,” or 
• “no risk,” as they often trigger high spam scores.

Proper formatting is also crucial. 

Emails that contain only images or excessive HTML elements without enough text can be flagged as spam. 

Always ensure a good balance of text and images to make the content appear natural. (Usually  60% of text goes well with 40% image content in the emails)

Furthermore, maintaining correct grammar and punctuation is essential, emails with excessive typos or broken sentences can be flagged as low-quality content, increasing the likelihood of being filtered as spam.

✅ Build a good sending history

A strong sending history improves email deliverability and reduces the chances of emails being flagged as spam. 

Email providers track your sending patterns, engagement rates, and spam complaints. 

A sudden spike in email volume, high bounce rates, or low engagement can damage your reputation, increasing your SpamAssassin score. 

To maintain a good history, gradually increase your sending volume (email warm-up) and keep your email list clean by removing inactive or invalid addresses.

AI-powered sales engagement tool like SmartReach.io helps businesses build and maintain a good sending history.

SmartReach.io increases email deliverability with AI email warm-up, audience segmentation, and email verification to prevent bounces and improve sender reputation. Its inbox rotation ensures a steady sending pattern, avoiding limits and strengthening sender history.

✅ Ensure proper email formatting and structure

Emails that are poorly formatted or have broken HTML can be flagged as suspicious by SpamAssassin. 

It’s important to include both a plain text and HTML version of your email to ensure compatibility across different email clients. 

A plain-text version increases legitimacy, as most spam emails are HTML-only.

Keeping subject lines professional and relevant to your message helps avoid unnecessary penalties.

Read more: How to Write Cold Email Subject Line & Body Copy?

✅ Limit the number of links and attachments

Spam filters evaluate the number and type of links in your email. 

Emails with too many links, especially shortened URLs (such as bit.ly or tinyurl), can appear suspicious and trigger spam filters. 

Ensure that all links direct users to reputable, trusted domains.

Attachments should also be used sparingly. 

Many email providers block attachments with executable files (.exe, .zip) or uncommon file formats due to security risks. 

If you need to share a document, consider using a trusted cloud-based service (e.g., Google Drive, Dropbox) and providing a secure link instead.

✅ Include a visible and easy-to-use unsubscribe option

One of the biggest red flags for SpamAssassin is when an email does not include an easy way for recipients to opt out. Sending unsolicited emails without an unsubscribe option increases spam complaints, which can hurt your email reputation. 

To stay compliant with email regulations like CAN-SPAM and GDPR, always include a clear and visible unsubscribe link at the bottom of your email. 

Allowing recipients to easily opt out reduces the chances of your emails being marked as spam, ultimately improving deliverability.

Conclusion

Maintaining a low SpamAssassin score is key to ensuring your emails land in the inbox rather than spam. 

While understanding how SpamAssassin evaluates emails is crucial, long-term success depends on following email best practices authenticating your domain, sending relevant and engaging content, and maintaining a strong sender reputation.

Using sales engagement tools like SmartReach.io can simplify this process by automating warm-ups, optimizing email sequences, and improving overall deliverability.

Try free for 14 days without any credit card.

SpamAssassin score: F.A.Q.s

What is SpamAssassin?

SpamAssassin is an open-source email filtering system that detects and blocks spam emails using various tests, including content analysis, header inspection, and Bayesian filtering. It assigns a spam score to emails based on multiple rules, helping mail servers determine whether to deliver, flag, or reject them.

What is a good score on SpamAssassin?

A good SpamAssassin score is below 5. Scores closer to 0 or negative values indicate a lower likelihood of being flagged as spam, whereas higher scores increase the chances of the email being filtered into the spam folder.

What is the recommended spam score?

The recommended threshold for SpamAssassin is 5 or lower. Most email servers mark emails with a score above 5 as spam. However, stricter configurations may use a lower threshold (e.g., 3) to minimize false negatives.

Is SpamAssassin any good?

Yes, SpamAssassin is highly effective in filtering out spam emails. It uses a combination of rule-based scoring, Bayesian filtering, and real-time blacklists to accurately detect spam. Many businesses and email providers use it to enhance email security and reduce junk mail.

What is the score rule for SpamAssassin?

SpamAssassin assigns a numeric score to an email based on various tests. Each rule carries a specific score, which is added up to determine the email’s final spam score. If the total score exceeds the configured threshold (typically 5), the email is classified as spam.

How do I improve SpamAssassin score?

To improve your SpamAssassin score, ensure proper email authentication (SPF, DKIM, DMARC), use engaging and relevant content, avoid spam trigger words, limit the number of links and attachments, and send emails from a trusted domain with a good sending history.

What is the whitelist in SpamAssassin?

The whitelist in SpamAssassin is a list of trusted email addresses or domains that are exempt from spam filtering. Emails from whitelisted senders receive a lower spam score, ensuring they reach the inbox without being flagged as spam.