Fax with Microsoft Power Automate — Using Our REST API

How it works

Power Automate's HTTP action is a general-purpose caller. You set the method to POST, the URI to /v1/faxes, add an Authorization header with your bearer key, and supply a JSON body containing a `to` number and either inline base64 or a public document_url. Any trigger — a new SharePoint file, a Dataverse row, a scheduled recurrence — can feed that action. For the return path, the When an HTTP request is received trigger generates a callback URL; you register it as a webhook endpoint at /dashboard/developers and subscribe it to the events you want, and our HMAC-signed posts then launch a flow. Both directions are plain signed HTTP, so the whole fax lifecycle lives inside your existing Microsoft automations.

What you can do

• ✓Send a fax from any Power Automate trigger with an HTTP action aimed at /v1/faxes
• ✓Feed a SharePoint or OneDrive file to the fax as a public document_url
• ✓Receive fax.delivered / fax.failed / fax.received on a When an HTTP request is received trigger
• ✓Post a delivered result to Teams or write it to a Dataverse table in the same flow
• ✓Add an Idempotency-Key so a flow retry never dispatches the fax twice
• ✓Verify the X-SFM-Signature HMAC in a Compose/expression step before trusting an event

Setup steps

1. 1Confirm the account is on Business or Enterprise so the API and webhooks are active
2. 2Create an API key at /dashboard/developers with faxes:send (add faxes:read to poll)
3. 3In a Power Automate cloud flow, add an HTTP action set to POST /v1/faxes
4. 4Add an Authorization: Bearer header and a JSON body with `to` and `document_url`
5. 5For inbound automation, add a When an HTTP request is received trigger and copy its URL
6. 6Register that URL at /dashboard/developers and select which events to forward

Example

# Power Automate: HTTP action
Method:  POST
URI:     https://www.sendfaxmail.com/v1/faxes
Headers: Authorization: Bearer sfm_live_xxxxxxxx
         Idempotency-Key: @{workflow()?['run']?['name']}
Body:
{ "to": "@{triggerBody()?['faxNumber']}", "document_url": "@{triggerBody()?['fileUrl']}" }

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