Terms of Use

By using SubjectLines you agree to these terms. The site provides free, as-is tools for evaluating and drafting email subject lines. Scores, spam-flagging and truncation previews are best-practice guidance based on published industry behavior — they are estimates, not guarantees of opens, deliverability or inbox placement.

Acceptable use

Use the tools for email you have the right to send. The site exists to improve honest email; using its output to disguise unsolicited bulk mail violates both the spirit of these terms and the anti-spam laws (CAN-SPAM, GDPR and peers) that govern your sending.

Liability

SubjectLines is provided without warranty of any kind. To the maximum extent permitted by law, the operators are not liable for any outcomes of emails you send — including deliverability results, open rates or recipient reactions — however related to the tools' guidance.

Last updated: October 2026.