---
ref: tool:lemlist/send-inbox-email
name: Send an email from the inbox
company: company:lemlist
workflows: []
access: [cli, api]
tags: [capability:send-email, category:sales-engagement, has:api, has:cli]
docs: https://developer.lemlist.com/api-reference/endpoints/inbox/send-email
updated: 2026-09-27
---

# Send an email from the inbox

Sends one email to a lemlist contact or lead from a connected mailbox, as a new message or as a reply in their latest thread.

Pass the sender's `sendUserId`, `sendUserEmail` and `sendUserMailboxId`, the
recipient's `contactId` or `leadId`, a `subject` and an HTML `message`. Set
`replyToActivityId` to an email activity id (`act_...`), or to `latest`, to
reply in the thread and reuse its subject. This sends a real email, so
confirm the recipient and text first.

## Set up

Use the first option your agent supports.

### CLI (official)

Install the command, then confirm it runs.

```sh
npm install -g @lemlist-official/cli
lemlist --version
```

Run `lemlist api POST /inbox/email`.

### API (official)

- Base URL: https://api.lemlist.com/api
- Endpoint: `POST /inbox/email`
- Auth: send the header `Authorization: Basic $LEMLIST_API_KEY`
- Get a key: https://app.lemlist.com/settings/integrations
- Docs: https://developer.lemlist.com/api-reference/getting-started/authentication

Before doing anything else, make one read-only call to confirm access.

## Rules

- Ask the user before anything that sends messages, costs money, or changes data.
- Never print API keys.