Free tool
Email subject line tester: check yours before you send
Paste a subject line. You get its length, spam-trigger words, capitals, punctuation, emoji, fake Re: and Fwd: prefixes, personalisation tokens and a simple checklist score.
Check your subject line.
These checks are writing guidelines. The length warning is an approximation that varies by email app, device and screen width. The spam-word list is a short heuristic, not a prediction of what any mail filter will do. We make no claim about open rates. Everything is worked out in your browser, and nothing you type is sent anywhere.
How to read the checks.
What the checks are
They are writing guidelines, not a test of what mail providers or readers will do. Providers look at your sender reputation, authentication, links and the body of the email, and no subject line fixes a weak sender. We make no claim about open rates, because the text of one line cannot promise them.
The score
The score counts seven simple checks, such as length, capitals and a fake Re: prefix. A full score does not make a subject line good. A low score is a prompt to read the line again, not a verdict. Spam-trigger words are flagged because they show up often in promotional email, and one word from the list rarely matters on its own.
Length
Phone inboxes cut subject lines off, and where they cut depends on the app, the device, the screen width and the font. Treat the 40 and 60 character marks as approximations, and put the words that matter first.
What usually helps
- Say what the email is about, in plain words.
- Make the subject a fair preview of the message.
- Skip capitals, stacked punctuation and strings of emoji.
- Use a name or token only when it adds meaning, and set a fallback so a missing field never shows as raw text.
Why fake Re: and Fwd: matter
A fake prefix implies a conversation that never happened. The FTC’s CAN-SPAM compliance guide says not to use deceptive subject lines, and it makes no exception for email between businesses.
For examples by situation, read our guide to cold email subject lines. For whole messages, see our cold email templates. If you would rather have the list, the sending setup and the copy handled for you, look at our cold email agency or our email automation services.
Want the whole email set up properly?
We build the list, set up the sending domains and write the copy for your approval. Prices are public, and we tell you first if your offer is not a fit for cold email.
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