Paste a subject line and body to highlight the phrases, capitals, punctuation and emoji that push mail toward the spam folder, grouped by why each one is a problem. Get a calmer rewrite in one click. Runs in your browser; nothing is uploaded.
Modern filters at Gmail, Outlook and Yahoo weigh authentication, sender reputation and how recipients engage with your mail far more than any single word. A clean subject line will not rescue a domain without DMARC. But wording still counts at the margin, especially for newer senders, smaller filters and corporate gateways, and it shapes how readers react, which feeds reputation in turn.
Treat this as a fast wording pass: the phrases that read as a pitch, manufactured urgency, shouting, and formatting habits filters have long associated with junk. Each flag comes with the reason and a plainer alternative.
"Cash bonus", "make money", "lowest price": they read like a pitch.
"Act now", "last chance", "limited time": state a real date instead.
"Free" once is fine; "100% free, no strings attached" is not.
"Guaranteed", "risk-free", "miracle": absolute claims invite distrust.
"Click here", "verify your account", "dear friend": phishing vocabulary, weighted most.
ALL-CAPS subjects, "!!!", emoji stacks, fake "Re:" prefixes and URL shorteners.
Only if wording was the problem, which is rarely the whole story. Check your domain's SPF, DKIM and DMARC with the domain check, and make sure you only mail people who asked to hear from you.
No. One natural use is fine. The problem is stacking offer language, putting it in capitals, or pairing it with urgency.
No. It is rule-based: trigger phrases are swapped for plainer wording and capitals and punctuation are calmed. Read it before sending; it fixes tone, not meaning.
Yes. Inbox Preview renders the same HTML in real Gmail, Outlook.com and Yahoo Mail accounts and screenshots the result, free.
Point an MCP client (Claude, Cursor, any agent) at https://powerline.ai/mcp and call check_spam_words, or hit the JSON endpoint directly. No key, no account.
curl -X POST https://powerline.ai/api/tools/spam-words \ -H "Content-Type: application/json" \ -d '{"subject": "Your October update", "body": "…", "rewrite": true}'
SPF, DKIM, DMARC, MX, MTA-STS, TLS-RPT, BIMI and blacklists in one run, scored out of 100 with a fix list.
Open .eml and .emlx files in the browser: rendered body, headers, authentication and attachments.
Check whether a domain, or the domain of an email address, is on a domain or URI blacklist.
Trace a message hop by hop, read the receiver's SPF/DKIM/DMARC verdicts and check DMARC alignment.
See how your HTML email actually renders in real Gmail, Outlook.com and Yahoo Mail accounts. Free screenshots.