How do images get scanned for text or phishing cues?

OCR (Optical Character Recognition) technology enables spam filters to \"read\" text embedded in images. This evolved in response to a classic evasion tactic: spammers would put their entire message in an image to bypass text-based filtering. Modern filters extract text from images and analyze it just as they would plain text-scanning for spam phrases, phishing language, and prohibited content that image embedding can no longer hide.

Beyond text extraction, filters analyze visual patterns and metadata. Images associated with known spam campaigns are fingerprinted. Logos mimicking banks or major brands (phishing indicators) are recognized. Unusual characteristics-images optimized to evade detection, hidden layers, steganographic content-raise suspicion. Even the ratio of image content to text content factors into analysis.

For legitimate senders, the implications are practical: don't try to hide text in images to evade filters-they'll catch it and penalize you for the attempt. Ensure images support your message rather than replace it entirely. Use standard formats (JPEG, PNG, GIF) without unusual optimization or embedded content. Image scanning closed the last major loophole in text-based filtering; there's no visual trick that sophisticated filters haven't learned to detect. Focus on sending legitimate content, not finding creative ways to disguise it.