Direct Destination

The Direct destination sends clinical documents using the Direct messaging protocol — the standard for secure, point-to-point healthcare communication in the United States. It is commonly used to transmit C-CDAs, referral letters, lab results, and discharge summaries between provider organizations.

Under the hood, Direct messages are S/MIME encrypted and transmitted over SMTP. The sender’s signing certificate proves identity, and the recipient’s encryption certificate (resolved via DNS or LDAP) ensures only the intended recipient can read the message.

Configuration

destination:
  type: direct
  direct:
    to: dr.smith@direct.goodhealth.org
    from: lab@direct.hospital.org
    smtp_host: direct-smtp.hospital.org
    smtp_port: 465
    certificate: ./certs/direct-signing.pem
    private_key: ./certs/direct-signing-key.pem
    content_type: application/xml
    tls:
      enabled: true
      ca_file: ./certs/direct-ca.crt

Properties

Property	Type	Required	Default	Description
`to`	`string`	Yes	—	Recipient’s Direct address (e.g., `provider@direct.example.org`).
`from`	`string`	Yes	—	Sender’s Direct address. Must be registered with your HISP.
`smtp_host`	`string`	Yes	—	SMTP host provided by your HISP for outbound Direct messages.
`smtp_port`	`int`	No	`465`	SMTP port for the Direct HISP relay.
`certificate`	`string`	No	—	Path to the sender’s X.509 signing certificate (PEM format).
`private_key`	`string`	No	—	Path to the private key corresponding to the signing certificate.
`content_type`	`string`	No	`application/xml`	MIME type of the message payload. Typically `application/xml` for C-CDA documents.
`tls`	`object`	No	—	TLS settings for the SMTP connection to the HISP.

Trust Framework

Direct messaging relies on a trust framework managed by Health Information Service Providers (HISPs):

Both sender and receiver must be registered with a HISP.
Signing certificates are issued by a Certificate Authority within the DirectTrust network.
The recipient’s encryption certificate is resolved automatically via DNS or LDAP lookups.
Messages are encrypted end-to-end — the HISP relays cannot read the content.

Complete Example

Send a C-CDA discharge summary to a referring physician via Direct:

id: discharge-summary
enabled: true
group: transitions-of-care

source:
  type: http
  port: 8443
  path: /discharge
  methods:
    - POST
  tls:
    cert_file: ./certs/server.crt
    key_file: ./certs/server.key
  auth:
    type: bearer
    token: ${DISCHARGE_TOKEN}

transformer: build-ccda.ts

destinations:
  - type: direct
    direct:
      to: dr.smith@direct.goodhealth.org
      from: discharges@direct.hospital.org
      smtp_host: direct-smtp.hospital.org
      smtp_port: 465
      certificate: ./certs/direct-signing.pem
      private_key: ./certs/direct-signing-key.pem
      content_type: application/xml
      tls:
        enabled: true
        ca_file: ./certs/direct-ca.crt