Fax Automation — Wire Faxing Into Your Own Software

How it works

An automated fax flow has two halves. Outbound: your system reacts to an event — a signed contract, a discharged patient, a closed invoice — by calling POST /v1/faxes with the recipient and a document, either as base64 or a public document_url that we fetch for you. Inbound and status: rather than poll, you register a webhook endpoint so fax.delivered, fax.failed, and fax.received events arrive at your server signed with HMAC-SHA256, letting you update a record or retry on failure the instant the result is known. Because the send endpoint reuses the same gates as the dashboard — quota, BAA, and number checks — an automated send obeys the same rules a person would, so nothing slips past your plan's limits.

What you can do

• ✓Trigger an outbound fax from a CRM, EHR, or billing event by calling /v1/faxes
• ✓Fax a document straight from a public link with document_url, no local upload step
• ✓Receive delivered, failed, and received results by webhook instead of polling
• ✓Reconcile or report by listing faxes through GET /v1/faxes on a schedule
• ✓Make retries safe end to end with an Idempotency-Key on every automated send
• ✓Inherit the account's quota, BAA, and number gates on every API-driven send

Setup steps

1. 1Move the account to Business or Enterprise so API and webhook features are active
2. 2Create a scoped API key at /dashboard/developers and store it in your app's secret manager
3. 3Identify the event in your system that should trigger a fax and call /v1/faxes from that handler
4. 4Send by document_url when the file already lives at a public link, or by base64 when you hold the bytes
5. 5Register a webhook endpoint for fax.delivered and fax.failed to capture the outcome automatically
6. 6Attach an Idempotency-Key per send and verify the webhook signature so the loop is safe to retry

Example

// Pseudocode: fax a signed contract, then let a webhook record the result
await fetch("https://www.sendfaxmail.com/v1/faxes", {
  method: "POST",
  headers: {
    "Authorization": "Bearer sfm_live_xxxxxxxx",
    "Idempotency-Key": contract.id,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    to: contract.recipientFax,
    document_url: contract.signedPdfUrl,
  }),
});
// fax.delivered / fax.failed then POSTs to your webhook endpoint.

Fax Automation — FAQ