Spam word checker
Paste a subject and body. We flag the phrases with a history of appearing in filtered mail, and the formatting patterns filters weigh more heavily than any word.
Checked against 107 phrases plus the formatting patterns filters weight. Nothing you paste leaves this tab.
The word list is the smallest part of the answer
Filters used to work on keywords, and the advice from that era has outlived the technology by fifteen years. SpamAssassin scored rules like that in the 2000s, and its descendants still run in front of plenty of corporate mail servers. Gmail and Microsoft moved on.
What replaced it is reputation. Your domain and IP carry a history. Authentication says whether you are who you claim. Engagement says whether people open, reply, delete or complain. Those signals dominate, and the text is a tiebreaker.
Which is why the findings are worth reading for a different reason. A subject with three exclamation marks and a promise nobody can keep does not fail a keyword test so much as it fails a person. The recipient marks it as spam, and the complaint is what actually costs you.
Two structural things do still carry real weight. A message that is one large image with a link and almost no text is a pattern spammers use to hide copy from text analysis. And mail with no unsubscribe wording breaks the law in several countries before any filter gets involved.
| Signal | How much it moves placement | Who controls it |
|---|---|---|
| Sender reputation | The largest single input | Your sending history |
| Authentication | Required by Google and Yahoo for bulk senders | Your DNS records |
| Complaint rate | Direct and fast | Consent and frequency |
| Bounce rate | Direct | List hygiene |
| Vocabulary and formatting | Small, and not nothing | The copy on this page |
Fixing a flagged subject line
Take the flags as a prompt to write plainly rather than a list of forbidden words. An offer that is genuinely free can say so. What reads badly is the stack: the free, the guarantee, the urgency and the capitals all in the same nine words.
Cut the shouting first. Exclamation marks and all-caps words do more damage with the reader than with the filter, and the reader is the one holding the report button.
Then check the claim. If the subject promises something the body cannot support, the complaint follows whatever the words were. The most reliable way to keep a good reputation is to send mail people expected.
Questions people ask
Is it safe to use the word free?
Yes, on its own. What looks bad is free next to guaranteed next to act now, in capitals, with three exclamation marks. One flag is a word; six is a pattern.
Does putting Re: in a cold subject line help?
It raises open rates and it is deception, and recipients who notice report it. We flag it for that reason: the complaint costs more than the opens are worth.
Should I avoid links in a first email?
One link is fine. A short message that is mostly links is the pattern worth avoiding, which is why we flag link density rather than link presence.
Do emojis in a subject line trigger filters?
Not by themselves. They do change how the line reads on a phone, and overuse correlates with the kind of mail people report, which is the mechanism that matters.
Good copy to a dead address goes nowhere
Wording is the smallest lever you have. The list under it decides whether any of this reaches a person.