Free tools
Email subject line tester
Type or paste your proposed subject line. Review feedback before campaign launch.
What this checks
Character count, word count, capitalization patterns, urgency phrases, and symbol density.
Why it matters
Subject lines affect opens and spam filtering. Testing reduces avoidable mistakes.
Results
Common issues
- ALL CAPS subjects or excessive punctuation that trigger filters.
- Hiding the value proposition after the mobile truncation point.
- Misleading subject lines that increase complaint rates.
How to fix
- Front-load the most important words within the first 40 characters.
- Match subject intent to body content and list consent.
- Pair subject review with SpamAssassin and unsubscribe checks.
How MailFleet helps
MailFleet template workflows let teams preview subjects alongside full message content before scheduling campaigns.
Related free tools
Delivery note: MailFleet helps users manage campaigns through their own sending providers. Delivery outcomes depend on sender reputation, DNS authentication, content quality, recipient engagement, list quality, provider rules, and mailbox filtering systems.
For regulatory context on commercial email in the United States, see the FTC CAN-SPAM compliance guide.
Frequently asked questions
Many clients truncate around 40–50 characters on mobile. Front-load the most important words.
Get started
Prepare and control campaigns with MailFleet
Run integrated diagnostics, manage providers, and monitor campaigns from a professional desktop app.
Available on
- Windows 10+
- macOS 12+
- Linux (DEB & RPM)
Same desktop experience across every platform — one workflow for your entire team.