Spam Word Checker for Email Subject Lines
Score your subject line against 60+ spam triggers before you hit send.
Spam filters score your subject line before a human ever sees it. This checker uses a heuristic word list — a guide, not a guarantee.
What are spam trigger words?
Email spam filters do not read your mind — they score your subject line. Certain words and phrases ("free", "guarantee", "act now", "$$$") appear so often in actual spam that filters treat them as warning signals. One trigger word will not doom you, but stacking several is how legitimate emails end up in the junk folder instead of the inbox.
How the score works
This checker scans your subject line against a built-in list of about sixty common trigger phrases, grouped into four families: pressure/urgency, money hype, overpromising, and shady clickbait. Each unique flag lowers the score, and the tool also checks capitalization ratio, exclamation marks, and length. It is a heuristic guide based on widely documented filter behavior — not a look inside Gmail's actual algorithm, which nobody outside Google can see.
How to use it
Type or paste your subject line and press Check. You get a 0–100 score with a verdict (Inbox-friendly, Risky, or Likely spam), your flagged words highlighted, and a plain-English fix for each category. Rewrite, re-check, and repeat until the flags are gone.
Quick wins
Keep subject lines between 40 and 50 characters so they display fully on phones. Use normal capitalization — ALL CAPS reads as shouting to both humans and filters. Skip the exclamation marks, or use at most one. And say what the email is actually about: specific beats hypey every single time.