Writing & Content · Free tool
Email Subject Line Tester
Test email subject lines for length, spam triggers, and emoji safety. Preview how they render on Gmail and iPhone Mail.
Updated April 2026
Characters
27
Desktop off / Mobile off
Words
5
Spam score
0%
Sentiment
Neutral
Inbox preview
A
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What it does
Test an email subject line for length, spam-trigger words, excessive punctuation, and emoji rendering. Previews how the line looks on iPhone Mail and Gmail's inbox, where most subject lines get truncated around 40–60 characters. Essential for newsletter campaigns and cold outreach.
For general headlines use headline analyzer. For ad character limits, ad copy length checker. Pair with character counter for a clean count.
How to use it
- Type or paste a subject line.
- Read the score and the flagged issues (length, spam words, emoji risk).
- Compare the iPhone and Gmail previews.
- Iterate until the score and previews both look clean.