Email subject line tester
Review your subject line and preview it on mobile.
Use the tool
Your draft and sample fields stay in this browser tab.
We count tool use, never inputs or results.
Enter text to see concrete observations.
Checks include English wording cues such as urgency, unsupported claims and vague links. Review each match in context. These observations cannot predict spam placement or delivery.
Text observations
Approximate narrow inbox line
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