Content Filtering
Spam filter analysis of email content including text, images, links, and HTML to identify spam characteristics.
Definition
Content filtering is the analysis of email content by spam filters to identify characteristics associated with spam. Filters examine the text, HTML code, images, links, and overall structure of emails. They look for spam triggers like suspicious phrases, excessive punctuation, hidden text, known malicious URLs, and other patterns that distinguish spam from legitimate mail.
Why It Matters
Your email content directly affects deliverability. Even with perfect authentication and reputation, spammy content can trigger filters and land you in the junk folder. Understanding what content filters look for helps you write emails that reach the inbox while still being compelling.
How It Works
Content filters use multiple techniques: keyword analysis (looking for spam phrases), URL reputation checking, image-to-text ratio analysis, HTML code inspection, Bayesian probability scoring, and comparison against known spam patterns. Each factor contributes to an overall spam score that determines inbox placement.
Best Practices
- 1Write natural, conversational copy without excessive hype
- 2Avoid ALL CAPS, excessive punctuation (!!!), and spam trigger phrases
- 3Maintain good text-to-image ratio (aim for 60/40 or better)
- 4Only link to reputable domains with good reputation
- 5Use clean HTML code without hidden elements or deceptive formatting