SMTP Sink Node

The smtpsink node sends an email via SMTP for each pipeline record, building recipients, subject, and body from record fields using template expressions.

Each record that passes through the sink triggers one email. Recipients, subject, and body are specified as templates that support {{$.field}} placeholders, allowing the email content to be fully dynamic based on record data. STARTTLS is enabled by default for encrypted transport.

Key Features

• Per-record email sending: each pipeline record triggers one outbound email
• Template expressions: use {{$.field}} placeholders in toTemplate, ccTemplate, subjectTemplate, and bodyTemplate to build dynamic content from record fields
• HTML and plain text support: set bodyContentType to text/html for rich HTML emails or text/plain for simple text
• STARTTLS support: encrypted transport via STARTTLS is enabled by default

Configuration

Field	Type	Required	Default	Description
host	String	Yes	—	SMTP server hostname
port	Integer	No	587	SMTP server port
credentialId	String	Yes	—	ID of username/password credentials in jobContext.otherProperties.
fromAddress	String	Yes	—	Sender email address (e.g. alerts@example.com)
toTemplate	String	Yes	—	Template expression for recipient(s). Supports {{$.field}} placeholders.
ccTemplate	String	No	—	Template expression for CC recipients. Supports {{$.field}} placeholders.
subjectTemplate	String	Yes	—	Template for the email subject. Supports {{$.field}} placeholders.
bodyTemplate	String	Yes	—	Template for the email body. Supports {{$.field}} placeholders.
bodyContentType	String	No	text/plain	MIME type of the body (text/plain or text/html)
useTls	Boolean	No	true	Enable STARTTLS

Template Expressions

Template fields support {{$.field}} placeholders that are evaluated against each pipeline record at runtime. For example, given a record:

{
  "alert_email": "oncall@example.com",
  "severity": "CRITICAL",
  "host": "web-server-01",
  "message": "Disk usage exceeded 90%"
}

The following configuration produces a fully dynamic email per record:

config:
  fromAddress: "alerts@example.com"
  toTemplate: "{{$.alert_email}}"
  subjectTemplate: "Alert: {{$.severity}} on {{$.host}}"
  bodyTemplate: "Host {{$.host}} reported: {{$.message}}"
  bodyContentType: "text/plain"

This would send an email to oncall@example.com with the subject Alert: CRITICAL on web-server-01 and the body Host web-server-01 reported: Disk usage exceeded 90%.

DAG Example

jobContext:
  otherProperties:
    smtp-cred:
      username: alerts@example.com
      password: mypassword
  metricTags: {}
  dlqConfig:

dag:
  - id: "source"
    commandName: "stdin"
    config:
      encodingType: "JSON_OBJECT"
    outputs:
      - "sink"

  - id: "sink"
    commandName: "smtpsink"
    config:
      host: "smtp.example.com"
      port: 587
      credentialId: "smtp-cred"
      fromAddress: "alerts@example.com"
      toTemplate: "{{$.alert_email}}"
      subjectTemplate: "Alert: {{$.severity}} on {{$.host}}"
      bodyTemplate: "Host {{$.host}} reported: {{$.message}}"
      bodyContentType: "text/plain"
      useTls: true

Related Nodes

• imapsource: Poll an IMAP mailbox and emit each email as an record
• sqssink: Send pipeline records as messages to an SQS queue