What Is SpamAssassin?

What Is SpamAssassin?

SpamAssassin is an open-source spam filtering system that analyzes emails and assigns spam scores based on various factors. It uses rule-based scoring, Bayesian filtering, network tests, and content analysis to evaluate emails.

SpamAssassin assigns points for spam characteristics (higher scores = more likely spam) and combines them into an overall spam score. Scores under 5.0 are generally considered acceptable, while scores 5.0 and above may be filtered as spam. SpamAssassin is widely used by email servers and ISPs to filter spam.

Test emails with our SpamAssassin test tool to check spam scores and identify issues before sending campaigns.

How SpamAssassin Works

1. Rule-Based Scoring

SpamAssassin uses thousands of rules that check for spam characteristics, assigning positive or negative points for each match.

2. Content Analysis

Analyzes email content for spam trigger words, suspicious patterns, HTML issues, and content characteristics.

3. Network Tests

Checks DNS blacklists, reverse DNS, and network reputation to identify known spam sources.

4. Bayesian Filtering

Uses statistical analysis to identify spam patterns based on word frequencies and content characteristics.

5. Header Analysis

Analyzes email headers for authentication results, routing anomalies, and suspicious patterns.

6. Score Calculation

Combines all test results into a single spam score, with higher scores indicating higher spam probability.

Scoring System

SpamAssassin uses a point-based scoring system:

Score Interpretation

• 0-3: Excellent - Very low spam probability
• 3-5: Good - Low spam probability
• 5-7: Moderate - May be filtered by some providers
• 7+: High - Likely to be filtered as spam

Score Components

Scores are calculated from:

• Content tests (spam words, patterns)
• Network tests (blacklists, DNS)
• Header tests (authentication, structure)
• HTML tests (structure, validity)
• Bayesian filtering results

Detailed Reports

SpamAssassin provides detailed reports showing which tests contributed to the score, helping identify and fix specific issues.

Testing with SpamAssassin

Testing emails with SpamAssassin helps identify spam issues before sending:

Our SpamAssassin Test Tool

Our SpamAssassin test tool provides:

• Spam score calculation
• Detailed test results
• Issue identification
• Recommendations for improvement

When to Test

• Before every email campaign
• After content changes
• When experiencing deliverability issues
• After template updates
• Regularly for monitoring

Best Practices

Test emails regularly, fix identified issues, and aim for scores under 5.0 for optimal deliverability.

Improving SpamAssassin Scores

1. Fix Authentication

Ensure proper SPF, DKIM, DMARC authentication. Missing authentication significantly increases spam scores.

2. Remove Spam Triggers

Use our spam words checker to identify and remove problematic words and phrases.

3. Validate HTML

Fix HTML issues using our HTML validator. Invalid HTML increases spam scores.

4. Check Blacklist Status

Monitor your blacklist status. Being on blacklists significantly increases scores.

5. Follow Best Practices

Use clean lists, maintain good engagement, and follow email best practices to improve scores.