Source type

Postmark Source Configuration

Postmark sources receive message stream, bounce, open, click, delivery, and inbound webhooks using Basic Auth credentials.

POSTMARKPOST, PUT, PATCH, DELETEUsernameEmail and messaging
Postmark webhooks documentationAll source types
Postmark sends webhook traffic to a FastHook source, FastHook validates the provider contract, records the request, and routes accepted events through connections to destinations.PostmarkProviderPOST, PUT, PATCH, DELETESignedFastHookSource URLPOSTMARKProvider credentialheader authVerify before queue401 on auth failure405 on wrong methodAcceptedRequestverified: trueConnections route the accepted request to destinationsFilters, transformations, retries, replay, and destination signatures stay downstream from source verification.

Postmark configuration

Create a Postmark source, keep POST and PUT and PATCH and DELETE enabled, and provide the configured Username, Password values for provider signature. FastHook uses these settings to validate each Postmark delivery before it enters the routing workflow.

Source Type

POSTMARK

Allowed methods

POST, PUT, PATCH, DELETE

Authentication

Provider signature

Credential fields

Username, Password

Postmark source config
{
  "type": "POSTMARK",
  "config": {
    "auth_type": "PROVIDER_SIGNATURE",
    "auth": {
      "provider": "POSTMARK",
      "username": "postmark",
      "password": "password"
    },
    "allowed_http_methods": ["POST","PUT","PATCH","DELETE"]
  }
}

Postmark request contract

FastHook verifies the Authorization Basic header against the configured username and password.

POSTPUTPATCHDELETE

Postmark headers

Preserve Authorization when sending Postmark test deliveries. FastHook evaluates this request context before accepting the payload, so missing or modified values remain visible as rejected requests instead of routed events.

Authorization

Basic Auth header sent by Postmark when configured.

Postmark setup

  1. Configure the Postmark webhook URL with the FastHook Source URL.
  2. Enable Basic Auth in Postmark and put the same username and password in FastHook.
  3. Use separate sources for inbound, bounce, and delivery streams when ownership differs.

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