Deliverability & Spam-Filter Considerations in Content

How your content can trigger spam filters. This section busts old myths ("spammy words") and reveals what actually triggers filters today, such as public link shorteners (like ), "phishy-looking" URLs, and a "low text-to-HTML" ratio.

16 questions in this topic

How do spam filters evaluate content today? Do “spam words” still matter? How does HTML cleanliness affect filtering? What’s the importance of text-to-code ratio? What’s a broken URL and why does it matter? Why should all URLs use HTTPS? What’s the difference between good and bad unsubscribe placement? How does reply-to address wording affect spam heuristics? How to check spam score pre-send (e.g., Mail-Tester, Glock)? What’s the difference between header and body content analysis? What is Bayesian filtering? What is content fingerprinting (hashes)? How can over-templating reduce reputation? What are content-based blocklists (SURBL, URIBL)? How do images get scanned for text or phishing cues? How can embedded links trigger security filters?

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