prerequisite 5 minutes

• Claude API key: visit console.anthropic.com → Settings → API Keys → “Create Key”. Copy it now. [citation:6]
• Billing: add at least $5 credit (Build plan). API calls cost ~$0.01–0.03 per email. [citation:6]
• Gmail label (optional but recommended): create a label like “Claude‑Draft” to filter only work‑relevant emails (prevents auto‑drafting everything). [citation:2]

In Zapier, click + Create Zap. Set up trigger:

• App: Gmail · Event: New Email [citation:2][citation:10]
• Connect your Gmail account (Zapier will prompt sign‑in).
• Label/mailbox: choose “Inbox” or the specific label you created. This avoids personal newsletters. [citation:2]

👉 Test trigger: select a recent real email to use as sample. This gives us data for later steps. [citation:2]

Action app: Anthropic (Claude) · Event: Send Message [citation:2][citation:6]

Connect your Anthropic account using the API key from step 1. [citation:6]

✏️ configure the prompt (this is where you shine)

User Message (prompt):
You are my executive assistant. Draft a reply to the email below.
- Use a friendly, professional tone — like me.
- Keep it concise but warm.
- If the email asks a question, answer based on general knowledge or suggest next steps.
- If you need more info, ask for clarification in the draft.
- Never invent specifics (dates, numbers) unless present in email.

Email subject: {{subject}}
Email body: {{body plain}}

Draft reply:

system prompt (optional) fill “System” with role: “You write in a warm, helpful brand voice. Signature: ‘Best, [Your Name]’.” [citation:6]

✅ Test step — Zapier will call Claude and show a generated reply. If it looks good, continue.

Add another action — app: Gmail · event: Create Draft Reply [citation:2][citation:5]

This is the magic: it attaches the draft to the exact email thread.

• From: select your email address.
• Body: click + and choose the “Response Content Text” from the Claude step. [citation:2]
• Thread: you need to map the original email thread. Click inside the field → “Add search step”. [citation:2]

Search configuration: Gmail step searches for the original email using its body/subject. Just map “Search string” to the original email’s body plain. Zapier automatically finds the right thread ID. [citation:2]

Test this step — you should see a draft appear in the Gmail thread you used as sample.

Turn your Zap ON. Now every new matching email (or labeled email) will have a Claude‑generated draft waiting. [citation:2]