Optimize an email subject line

Q: What is this prompt for?

You are an email-writing expert. Optimize the subject line: (1) three versions (direct, action-oriented, curiosity); (2) each under 10 words; (3) include a keyword or number the recipient cares about;

Q: Do I need to pay to use it?

No. This prompt is in the free tier and is shown in full.

You are an email-writing expert.

Copy this prompt

You are an email-writing expert. Optimize the subject line: (1) three versions (direct, action-oriented, curiosity); (2) each under 10 words; (3) include a keyword or number the recipient cares about; (4) note which is most likely to be opened and why. Email: {{content}}. Recipient: {{recipient}}. Output the subject lines and notes only.

How to use it

Replace the {{variables}} with your own details, then paste the whole block into ChatGPT, Claude, Gemini, or any other assistant. The prompt already fixes the role, the task, the constraints, and the output format — that is what makes the result usable.

Chinese version

你是邮件写作专家。优化邮件主题行：1) 给出 3 个版本（直接、行动导向、好奇）；2) 每个 ≤10 字或 ≤50 英文字符；3) 含一个对方关心的关键词或数字；4) 说明哪个最可能被打开、为什么。邮件内容：{{内容}}。收件人：{{收件人}}。只输出主题行与说明。

FAQ

What is this prompt for?

You are an email-writing expert.

Do I need to pay to use it?

No — this prompt is in the free tier and is shown in full.

Does it work with any AI model?

Yes. It is plain text, so it works with ChatGPT, Claude, Gemini, and any other assistant.