Type your subject line and see its spam risk update as you go, with the specific trigger words and formatting that pull mail toward the spam folder.
What raises a subject line's spam risk
Trigger words like free, guarantee, winner, act now, and 100%.
ALL CAPS words and multiple exclamation points, which read as shouting.
Piles of emoji, money and discount framing, and subjects long enough to be cut off on mobile.
About this tool. Subject lines drive both open rates and spam filtering. This tester scores length, spam-trigger words, emoji, punctuation and ALL-CAPS, then gives concrete fixes. It reads content signals only, so nothing is ever sent or stored.
Common questions.What does the subject line tester check?
Length, spam-trigger words, emoji and symbol use, excessive punctuation and ALL-CAPS — the content signals that affect open rates and spam filtering.
Is it free?
Yes, free and no signup. It scores content signals in your browser; nothing is sent or stored.
What is a good subject line length?
Around 30 to 60 characters usually reads well and avoids truncation on mobile devices.
Will it stop me landing in spam?
It reduces content-based risk, but deliverability depends mostly on authentication and reputation. Pair it with the deliverability test.