> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wirebox.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# Sending Outbound Email

> How to send new emails and reply to existing conversation threads.

Agents can initiate new email conversations or reply to existing threads using the `POST /api/v1/mail/send` endpoint.

***

### Replying to a Conversation Thread

When replying to a customer, always include the `thread_id` from the incoming message. Wirebox automatically:

1. Sets the proper RFC-5322 `In-Reply-To` and `References` headers.
2. Prefixes the Subject line with `Re:` if not already present.
3. Groups the reply into the existing thread for both parties.

<CodeGroup>
  ```bash cURL theme={null}
  curl -X POST https://api.wirebox.sh/api/v1/mail/send \
    -H "Authorization: Bearer $WIREBOX_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "agent": "eva",
      "to": ["alex@example.com"],
      "subject": "Re: Question regarding my API quota",
      "text": "Hello Alex,\n\nI have upgraded your organization quota to 50,000 requests/month.\n\nBest regards,\nEva",
      "thread_id": "thrd_01J8XYZ987ABC"
    }'
  ```

  ```python Python theme={null}
  import os
  import requests

  API_KEY = os.getenv("WIREBOX_API_KEY")

  response = requests.post(
      "https://api.wirebox.sh/api/v1/mail/send",
      headers={"Authorization": f"Bearer {API_KEY}"},
      json={
          "agent": "eva",
          "to": ["alex@example.com"],
          "subject": "Re: Question regarding my API quota",
          "text": "Hello Alex,\n\nI have upgraded your quota.\n\nBest regards,\nEva",
          "thread_id": "thrd_01J8XYZ987ABC"
      }
  )
  print("Response:", response.json())
  ```
</CodeGroup>

***

### Initiating a New Conversation

To send an outbound message that starts a fresh thread, omit the `thread_id`:

```bash cURL theme={null}
curl -X POST https://api.wirebox.sh/api/v1/mail/send \
  -H "Authorization: Bearer $WIREBOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "agent": "eva",
    "to": ["partner@company.com"],
    "subject": "Meeting follow-up and action items",
    "text": "Hi team, here is the summary of our sync today...",
    "html": "<p>Hi team, here is the summary of our sync today...</p>"
  }'
```