Email
Email Subject Line Tester
Check a subject line for length, spam triggers and readability.
Runs in your browser. No email content is transmitted.
About this tool
Free email subject line tester. Score a subject line for length, spammy phrasing, capitals and punctuation so more of your email reaches the inbox and gets opened.
Frequently asked questions
How long should a subject line be?
Around 30–60 characters, so it is not truncated on mobile inboxes.
What makes a subject spammy?
ALL CAPS, multiple exclamation marks, and phrases like "act now", "free", "guarantee" and "risk-free" all raise spam scores.
Does the subject affect deliverability?
It can. Content filters weigh the subject heavily, so a truthful, specific line is both better for opens and safer for filters.
Need more than a tool?
HostingSwift runs the servers too — VPS, web hosting, email, DNS and streaming, with a free tier to start.