Email Tools
Email Subject Line Tester
Review a subject line for length, truncation, spam wording and tone.
✓ Free
✓ No account
◉ Runs on this device
Email Tools
Powering up the tool…
TOOL EMAIL-SUBJEC
What this tool does
About the email subject line tester
Rule-based checks with the mobile preview shown — honest about what no subject tester can promise.
How to use it
- Type the subject line.
- Read the checks: length bands, spam vocabulary, caps, emoji, fake prefixes.
- Check the mobile preview — the first 40 characters carry the open.
- Front-load the words that matter and re-test.
Useful for
- Test the newsletter subject before it goes to 40,000 inboxes.
- See exactly where mobile clients will cut you off.
- Catch the !!! and FREE that filters have hated for a decade.
Straight answers
Email Subject Line Tester FAQ
What subject length actually works?
Under ~45 characters survives most mobile clients, which is where the majority of opens happen. Longer isn’t fatal — it just means your ending is invisible, so the tester shows precisely what survives.
Can any tool guarantee inbox placement?
No, and distrust any that implies it: placement is dominated by sender reputation, authentication and list quality. A subject line can only avoid own-goals — which is the honest job this tester does.