`send_email`

Send an email via the Resend API or SMTP.

Parameters

Common Parameters

providerstringdefault "resend": Email provider: "resend" or "smtp".
tostring or arrayrequired: Recipient email address(es). Supports ${ctx.key} interpolation.
subjectstringrequired: Email subject line. Supports interpolation.
fromstringdefault env SENDER_EMAIL or "[email protected]": Sender email address.
htmlstring: HTML body content. Supports interpolation.
textstring: Plain text body content. Supports interpolation.
ccstring or array: CC recipient(s).
bccstring or array: BCC recipient(s).
reply_tostring or array: Reply-To address(es).
timeoutnumberdefault 30: Request timeout in seconds.
output_keystringdefault "email": Prefix for context output keys.

Resend-specific Parameters

Parameter	Type	Required	Default	Description
`api_key`	string	no	env `RESEND_API_KEY`	Resend API key.

SMTP-specific Parameters

Parameter	Type	Required	Default	Description
`smtp_server`	string	no	env `SMTP_SERVER`	SMTP server hostname.
`smtp_port`	number	no	env `SMTP_PORT` or provider default	SMTP port (587 for STARTTLS, 465 for TLS, 25 for none).
`smtp_username`	string	no	env `SMTP_USERNAME`	SMTP authentication username.
`smtp_password`	string	no	env `SMTP_PASSWORD`	SMTP authentication password.
`smtp_tls`	string	no	`"starttls"`	TLS mode: `"starttls"` (default), `"tls"` (implicit), or `"none"`.

Context Output

{output_key}_status — HTTP status code (Resend) or SMTP response code.
{output_key}_data — Response body (Resend JSON) or SMTP response details.
{output_key}_success — true on success.

Environment Variables

Variable	Description
`RESEND_API_KEY`	Resend API key (fallback when `api_key` is not in config)
`SENDER_EMAIL`	Default sender address (fallback when `from` is not in config)
`SMTP_SERVER`	SMTP server hostname
`SMTP_PORT`	SMTP server port
`SMTP_USERNAME`	SMTP authentication username
`SMTP_PASSWORD`	SMTP authentication password

Examples

Resend API

local flow = Flow.new("send_email_resend")

flow:step("send", nodes.send_email({
    to = env("SENDER_EMAIL"),
    subject = "Welcome to IronFlow!",
    html = "<h1>Welcome!</h1><p>Your workflow engine is ready.</p>",
    text = "Welcome! Your workflow engine is ready."
}))

flow:step("log", nodes.log({
    message = "Email result: success=${ctx.email_success}, data=${ctx.email_data}"
})):depends_on("send")

return flow

SMTP

local flow = Flow.new("send_email_smtp")

flow:step("send", nodes.send_email({
    provider = "smtp",
    to = env("SENDER_EMAIL"),
    subject = "IronFlow SMTP Test",
    html = "<h1>Hello!</h1><p>Sent via SMTP.</p>",
    text = "Hello! Sent via SMTP."
}))

return flow

Multiple recipients

flow:step("notify_team", nodes.send_email({
    to = { "[email protected]", "[email protected]" },
    from = "[email protected]",
    subject = "Deploy complete: ${ctx.version}",
    html = "<p>Version <b>${ctx.version}</b> deployed.</p>",
    cc = "[email protected]",
    output_key = "deploy_email"
}))