Skip to content

Home Topics Email Deliverability Content filters

Email Deliverability · Content filters

How to set up spam filter content triggers: step-by-step guide (2026)

Short answer

To set up spam filter content triggers: Keep a healthy text-to-image ratio and always include a plain-text part; Link to your own domain; avoid shorteners and tracking domains with poor reputation; Make link text match the destination. Then test rendering and spam scores before sending.

Reputation dominates, but content still tips borderline decisions and drives the complaints that build reputation in the first place.

How to implement spam filter content triggers#

  1. Keep a healthy text-to-image ratio and always include a plain-text part.
  2. Link to your own domain; avoid shorteners and tracking domains with poor reputation.
  3. Make link text match the destination.
  4. Test rendering and spam scores before sending.

How to verify it worked#

Send a test message to seed mailboxes at Gmail, Outlook, and Yahoo, then inspect the Authentication-Results and delivery headers. Repeat after any DNS or sending-platform change.

Common mistakes#

  • Image-only emails.
  • Tracking links on a shared domain used by spammers.

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.

Analyse your own setup

All analysers
Technical analysis

Email header analyser

Read authentication, DMARC alignment, and hop-by-hop delays from raw headers.

Runs in your browser
Technical analysis

Warm-up schedule planner

Build a day-by-day ramp that respects per-mailbox ceilings.

Runs in your browser

Keep reading on Content filters