Email Subject Line Analyzer Online
The subject line is the first thing a recipient sees. Too long — it gets cut off. Too short — it fails to grab attention. Check how your subject looks across different email clients before hitting send.
Frequently asked questions
What is the optimal subject line length?
The recommended length is 40–50 characters. This ensures the subject is fully visible on mobile devices. Subjects longer than 60 characters are truncated in most email clients.
What is a preheader?
A preheader is the text visible next to the subject line in the inbox before the email is opened. It is set in the email HTML. Typically 80–100 characters. It reinforces the subject line and improves open rates.
Which words trigger spam filters?
Spam filters flag words like "free", "urgent", "limited time", and "win", as well as excessive exclamation marks, ALL CAPS, and too many emojis. The tool checks for the most common triggers.
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