---
ref: tool:instantly/reply-to-email
name: Reply to an email
company: company:instantly
workflows: [workflow:cold-email-reply-triage, workflow:outbound-demo-engine]
access: [api]
tags: [capability:send-email, category:sales-engagement, has:api]
docs: https://developer.instantly.ai/api-reference/email/reply-to-an-email
updated: 2026-10-11
---

# Reply to an email

Sends a reply to an email in an Instantly inbox from one of the workspace's connected sending accounts.

Note: Sends a real email: confirm the text first. It only replies to an existing email, whose `id` goes in `reply_to_uuid`; it can't start a new thread.

## Set up

Use the first option your agent supports.

### API (official)

- Base URL: https://api.instantly.ai
- Endpoint: `POST /api/v2/emails/reply`
- Auth: send the header `Authorization: Bearer $INSTANTLY_API_KEY`
- Get a key: https://app.instantly.ai/app/settings/integrations
- Docs: https://developer.instantly.ai/getting-started/authorization

Before anything else, confirm access with the cheapest read-only call, like a list or a search. Never send or change anything to test access.

## Rules

- Ask the user before anything that sends messages, costs money, or changes data, and say how many records it touches. One approval covers a batch the user has seen.
- Never print API keys.