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WEBHOOK
fax.queued
{
  "id": "evt_8aZqRm4yT3vK7pNxJ2bH9c",
  "created": 123,
  "data": {
    "object": {
      "id": "<string>",
      "to": "<string>",
      "pages": 123,
      "error_code": "<string>",
      "error_subcode": "<string>",
      "error_message": "<string>",
      "max_attempts": 3,
      "attempts": [
        {
          "attempt_number": 2,
          "started_at": "2023-11-07T05:31:56Z",
          "completed_at": "2023-11-07T05:31:56Z",
          "duration_ms": 123,
          "error_code": "<string>",
          "error_subcode": "<string>",
          "error_message": "<string>"
        }
      ],
      "webhook_url": "<string>",
      "idempotency_key": "<string>",
      "tags": {},
      "csid": "<string>",
      "submitted_at": "2023-11-07T05:31:56Z",
      "completed_at": "2023-11-07T05:31:56Z",
      "created_at": "2023-11-07T05:31:56Z",
      "updated_at": "2023-11-07T05:31:56Z"
    }
  }
}

Documentation Index

Fetch the complete documentation index at: https://mintfax.com/docs/llms.txt

Use this file to discover all available pages before exploring further.

​
When it fires

Once, immediately after POST /faxes returns 201. The credit hold has been placed, the fax record exists, and the job to dispatch to a carrier is queued. fax.queued is the earliest confirmation your handler will receive that mintfax has taken responsibility for the fax. After this, expect one or more fax.sending events, then exactly one of fax.delivered or fax.failed.

​
What your handler should do

  • Record the fax ID against whatever business object triggered the send (an order, a patient record, a contract).
  • If you tagged the fax via the tags field on submit, this payload carries those tags - good for routing back to the originating context.
  • Do not bill the customer or update success state yet. The fax has been accepted, not delivered.

Authorizations

​
Authorization
string
header
required

API key as Bearer token. Use an account key (mfx_acct_...) for /account/* endpoints, and an environment key (mfx_test_... for sandbox, mfx_live_... for live) for /environment/*, /faxes, /webhooks, and /events.

Body

application/json

Event delivery to your subscribed webhook endpoint.

Webhook delivery for fax.queued.

​
id
string
required

Event identifier (evt_-prefixed). Stable across retry attempts.

Example:

"evt_8aZqRm4yT3vK7pNxJ2bH9c"

​
type
enum<string>
required

Event type. Always fax.queued for this delivery.

Available options:
fax.queued
​
created
integer
required

Unix epoch seconds when the event was generated.

​
data
object
required

Response

2XX

Acknowledged. mintfax treats any 2xx response as a successful delivery.

Last modified on May 14, 2026