Sending Outbound Email - Wirebox

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:

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

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"
  }'

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())

Initiating a New Conversation

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

cURL

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>"
  }'