Content filtering evaluates message text, HTML, links, and attachments for spam patterns: deceptive phrasing, URL shorteners, image-only bodies, mismatched link text, and known malicious domains.
What good looks like#
- Done: Keep a healthy text-to-image ratio and always include a plain-text part.
- Done: Link to your own domain; avoid shorteners and tracking domains with poor reputation.
- Done: Make link text match the destination.
- Done: Test rendering and spam scores before sending.
What bad looks like#
- Seen in audits: Image-only emails.
- Seen in audits: Tracking links on a shared domain used by spammers.
How to move from bad to good#
Work through the good list in order and re-verify after each change. Most teams find one or two items from the bad list already present; fixing those usually produces the largest improvement.
Frequently asked questions#
Are spam trigger words still a thing?
Much less than a decade ago. Modern filters are statistical and reputation-weighted. Deceptive intent matters more than any single word.