SMTP Email Alerts

The SMTP Executor sends email notifications when triggered by any Krill event chain. Wire it to a threshold trigger, a cron timer, a logic gate, or any other trigger to get email alerts when conditions are met.

How It Works

The SMTP executor is a child of any trigger node. When the parent fires, the executor builds an email from its configured source DataPoint (subject = DataPoint name, body = current value + timestamp) and sends it via your SMTP relay.

Execution chain example:

DataPoint (temperature) → HighThreshold (> 30) → SMTP (send alert)

When the temperature DataPoint exceeds 30, the threshold fires, the SMTP executor sends an email with the current value.

Configuration

Add an SMTP executor as a child of any trigger or data-connected node. The editor exposes these fields:

Field	Description	Default
Host	SMTP relay hostname (e.g., smtp.gmail.com)	(required)
Port	SMTP port	587
Username	SMTP auth username (often your email address)	(optional if relay allows unauthenticated)
Password	SMTP auth password or app-specific password	(optional)
From Address	Sender address (defaults to username if empty)	(optional)
To Address	Recipient address	(required)

TLS Behavior

• Port 587 (default): Uses STARTTLS upgrade
• Port 465: Uses implicit SSL/TLS
• Other ports: Uses STARTTLS

Source DataPoint

Wire a DataPoint as a source to include its name and current value in the email. Without a source, the email body is a generic “SMTP executor node was executed” message.

Gmail Setup

1. Enable 2-factor authentication on your Google account
2. Generate an App Password for “Mail”
3. Configure the SMTP node:
   • Host: smtp.gmail.com
   • Port: 587
   • Username: your.email@gmail.com
   • Password: (the 16-character app password)
   • From: your.email@gmail.com
   • To: (recipient)

Troubleshooting

“SMTP host is not configured” — The host field is empty. Enter your relay hostname.

“Recipient address is not configured” — The To Address field is empty.

Connection timeout — Verify the host and port are reachable from your Krill server. Try telnet smtp.gmail.com 587 from the Pi.

Authentication failed — Double-check username and password. For Gmail, you must use an App Password, not your regular password.

“SMTP error: …“ — The error message from the mail server is shown in the node’s error field. Check the server logs for details: journalctl -u krill -f.

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Last verified: 2026-04-03