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

# Sending email

> Send, reply, and forward — with clean threading and idempotency.

## Send a message

```bash theme={null}
curl -X POST https://api.sentvia.ai/v1/messages \
  -H "Authorization: Bearer sv_live_…" -H "Content-Type: application/json" \
  -d '{
    "inbox_id": "INBOX_ID",
    "to": ["customer@example.com"],
    "cc": [],
    "subject": "Your order shipped",
    "text": "Tracking: 1Z…",
    "html": "<p>Tracking: <b>1Z…</b></p>"
  }'
```

```json Response theme={null}
{ "id": "m_…", "thread_id": "t_…", "direction": "outbound",
  "from_addr": "support-bot@mail.sentvia.ai", "subject": "Your order shipped" }
```

| Field                       | Notes                                              |
| --------------------------- | -------------------------------------------------- |
| `inbox_id`                  | The sending inbox (required).                      |
| `to`, `cc`, `bcc`           | Arrays of addresses. At least one `to` required.   |
| `subject`                   | Required.                                          |
| `text` / `html`             | Provide either or both.                            |
| `attachments`               | Base64 — see [Attachments](/guides/attachments).   |
| `in_reply_to`, `references` | Set these to thread into an existing conversation. |
| `client_id`                 | Optional idempotency key (see below).              |

## Reply & forward

Replying derives the recipient, subject, and threading headers from the original
message — you only supply the body:

```bash theme={null}
curl -X POST https://…/v1/messages/MESSAGE_ID/reply \
  -H "Authorization: Bearer sv_live_…" -H "Content-Type: application/json" \
  -d '{ "text": "Happy to help — here are the next steps.", "reply_all": true }'
```

Forward to new recipients with `POST /messages/{id}/forward`.

## Idempotency

Pass a unique `client_id` to make sends safe to retry — a repeated `client_id`
returns the original message instead of sending a duplicate:

```json theme={null}
{ "inbox_id": "…", "to": ["a@b.com"], "subject": "Hi", "text": "…", "client_id": "order-4821-confirm" }
```

## Suppression & blocking

Before sending, SentVia drops recipients that are **suppressed** (a prior hard
bounce or complaint) or on your [block list](/guides/allow-block-lists). If no
deliverable recipient remains, the send returns `422` with the blocked addresses —
protecting your sending reputation automatically.