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

# Attachments & storage

> Send and receive files, and how storage limits work.

## Sending attachments

Include a base64-encoded `attachments` array on `POST /messages` (or reply/forward):

```json theme={null}
{
  "inbox_id": "…",
  "to": ["customer@example.com"],
  "subject": "Your invoice",
  "text": "Attached.",
  "attachments": [
    { "filename": "invoice.pdf", "content_type": "application/pdf", "content_base64": "JVBERi0…" }
  ]
}
```

## Receiving attachments

Inbound attachments are stored and surfaced on the message — both in the webhook
payload and on `GET /messages/{id}` / `GET /threads/{id}`:

```json theme={null}
"attachments": [
  { "id": "a_…", "filename": "receipt.pdf", "mime_type": "application/pdf",
    "size_bytes": 48213, "url": "https://…signed…" }
]
```

The `url` is a **short-lived signed download link** — fetch the bytes directly from
storage, no extra auth needed. You can also mint a fresh link any time with
`GET /attachments/{id}`.

## Size limit

Email providers cap message size, so a single email's attachments must fit within
**\~7 MB** (the base64-encoded message stays under the 10 MB provider limit).
Oversized sends return `413 attachment_too_large` — caught before sending, never a
silent failure.

<Note>
  Need to move bigger files? Talk to us about large-file support (direct-to-storage
  uploads) on higher plans.
</Note>

## Storage limit

Total attachment storage is a **per-plan cap**:

| Plan     | Storage |
| -------- | ------- |
| Free     | 1 GB    |
| Pro      | 20 GB   |
| Scale    | 100 GB  |
| Business | 500 GB  |

Sending an attachment that would exceed your cap returns `402 storage_limit_reached`.
Inbound mail is **never rejected** — it's always stored, and the dashboard warns
you as you approach the limit. Track usage on the [Overview](https://console.sentfrom.ai).