Smart Subjects AI-Powered Subject Lines & Preview Texts

Smart Subjects helps you quickly generate effective, on-brand email subject lines and preview text using AI, based on your newsletter content and past performance.

How it works

When you’re on the Preview and Schedule step, the Email Subject and Preview Text fields include a Generate with AI (✨) icon. The AI draws on your newsletter’s themes and headlines, plus your top-performing past subject lines, to suggest options. You can edit, refine, or regenerate suggestions until you’re satisfied.

How to use Smart Subjects

1. Compose your newsletter as usual, then click Preview and Schedule.
2. In the Email Subject or Preview Text field, click the AI icon.
3. The field shows “Generating…” and then populates with a suggestion.
4. Edit, refine, or regenerate — then schedule as normal.

If you’re not scheduling right away, save your draft so the generated subject line and preview text aren’t lost.

Best practices built in

The generator is designed to:

• avoid spam trigger words and phrases;
• keep subject lines concise, simple, and attention-grabbing;
• learn from your top 5 performing subject lines to optimize open rates over time.

Related

• Test two subject lines against each other with A/B Tests on Email Subject Lines.
• Personalize subject lines with merge tags.

Prefer to have it done for you? The Letterhead assistant (early access — rolling out to select accounts) can read a draft back and revise its subject line or preview text for you in conversation — see how the assistant works. For everything else you can do, see Working in Emails.