SMTP Destination

The SMTP destination sends outbound email through any standard SMTP server, making it a natural fit for critical alerts, lab result notifications, scheduled reports, and other clinical communication that needs to reach a human inbox.

The subject line supports variable interpolation, so each email can include dynamic context from the message being processed.

Configuration

destination:
  type: smtp
  smtp:
    host: smtp.hospital.org
    port: 587
    from: [email protected]
    to:
      - [email protected]
      - [email protected]
    subject: "CRITICAL: Lab result for ${PATIENT_ID}"
    cc:
      - [email protected]
    content_type: text/html
    auth:
      username: ${SMTP_USER}
      password: ${SMTP_PASSWORD}
    tls:
      enabled: true

Properties

Property	Type	Required	Default	Description
`host`	`string`	Yes	—	SMTP server hostname or IP address.
`port`	`int`	No	`587`	SMTP port. Common values: `25` (relay), `465` (implicit TLS), `587` (STARTTLS).
`from`	`string`	Yes	—	Sender email address.
`to`	`string[]`	Yes	—	One or more recipient email addresses.
`subject`	`string`	Yes	—	Email subject line. Supports `${VAR}` interpolation from message metadata.
`cc`	`string[]`	No	—	Carbon-copy recipients.
`bcc`	`string[]`	No	—	Blind carbon-copy recipients.
`content_type`	`string`	No	`text/plain`	Body MIME type: `text/plain` or `text/html`.
`auth`	`object`	No	—	SMTP authentication credentials.
`tls`	`object`	No	—	TLS configuration for the SMTP connection.

Authentication

auth:
  username: ${SMTP_USER}
  password: ${SMTP_PASSWORD}

TLS

Property	Type	Required	Default	Description
`enabled`	`bool`	No	`true`	Enable STARTTLS or implicit TLS depending on the port.
`insecure_skip_verify`	`bool`	No	`false`	Skip server certificate validation. Not recommended for production.

Complete Example

Send an HTML email whenever a critical lab result is detected:

id: critical-lab-alerts
enabled: true
group: laboratory

source:
  type: tcp
  port: 6661
  content_type: hl7v2
  mllp: true

transformer: critical-lab-filter.ts

destinations:
  - type: smtp
    smtp:
      host: smtp.hospital.org
      port: 587
      from: [email protected]
      to:
        - [email protected]
        - [email protected]
      subject: "CRITICAL: Abnormal ${TEST_NAME} for MRN ${MRN}"
      cc:
        - [email protected]
      bcc:
        - [email protected]
      content_type: text/html
      auth:
        username: ${SMTP_USER}
        password: ${SMTP_PASSWORD}
      tls:
        enabled: true