Mailfois
Free tool

Email spam checker

Paste your subject and body to score the spam risk in your content — trigger words, shouty capitals, punctuation and link balance — before you send. Runs in your browser; nothing is uploaded.

Content safety / 100

Beyond content: authentication

Real inbox placement also depends on SPF, DKIM and DMARC on your sending domain. Those are DNS records that need a server-side lookup, so they sit outside this in-browser tool — a domain authentication checker is on the Mailfois roadmap.

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What a content spam score can and can't tell you

Spam filters weigh hundreds of signals. Roughly, they split into two groups: content (the words, formatting and links in your email) and infrastructure (your sending domain's authentication, reputation and how people engage with you). This tool covers the first group — the part you can fix by editing the email. It can't see your domain records or reputation, so a clean score here means "no obvious content red flags," not "guaranteed inbox."

The content red flags it looks for

  • Trigger words — free, guarantee, act now, winner, cash and friends, especially stacked together.
  • ALL CAPS — shouty words and subjects read as spam to filters and people alike.
  • Punctuation — multiple exclamation marks, rows of dollar signs, excessive symbols.
  • Link balance — a wall of links with little text, or naked shortened URLs.

Frequently asked questions

What words trigger spam filters?

Free, guarantee, act now, winner, cash, risk-free, 100% — worse with capitals and exclamation marks. Treat as warnings.

Does a good score guarantee the inbox?

No — content is only half the picture. Authentication, reputation and list quality matter too.

How do I check SPF, DKIM and DMARC?

They're DNS records needing a server-side lookup; a checker is on our roadmap. Your platform's setup area usually shows their status.

Clean the copy, then run everything through the full pre-send checker.

Every pre-send check in one place.

Open the pre-send checker