Email Route - Coreflux Documentation

Email Overview

The EMAIL route sends templated emails in response to MQTT messages. It’s the simplest way to turn a broker event — a critical alarm, a daily report, a user notification — into a message that reaches a person’s inbox.

Like an auto-reply rule in your mailbox. When a message lands on a topic you’re watching, the route fills in a template and sends the email for you — no manual step required.

When to use it

Alert an operations team the moment a critical alarm fires.
Email a stakeholder a daily or shift report.
Notify an individual user using an address pulled from the message payload.

Let’s look at how to define an email route, starting with the most common scenarios.

Quick Start

Critical alert
Dynamic recipient
Report with images

Send an immediate alert to a fixed team address when a critical event arrives:

DEFINE ROUTE CriticalAlerts WITH TYPE EMAIL
    ADD SMTP_CONFIG
        WITH HOST "smtp.gmail.com"
        WITH PORT '587'
        WITH USERNAME "alerts@company.com"
        WITH PASSWORD "app-password-here"
        WITH USE_TLS "true"
    ADD EVENT criticalNotify
        WITH SOURCE_TOPIC "alerts/critical/+"
        WITH TEMPLATE_PATH "/templates/critical_alert.html"
        WITH SUBJECT "CRITICAL: {value.json.alert_type}"
        WITH RECIPIENT "ops-team@company.com"

Send to an address taken from the message payload:

DEFINE ROUTE UserNotifications WITH TYPE EMAIL
    ADD SMTP_CONFIG
        WITH HOST "smtp.office365.com"
        WITH PORT '587'
        WITH USERNAME "noreply@company.com"
        WITH PASSWORD "secure-password"
        WITH USE_TLS "true"
    ADD EVENT userNotify
        WITH SOURCE_TOPIC "users/+/notifications"
        WITH TEMPLATE_PATH "/templates/user_notification.html"
        WITH SUBJECT "Hello {value.json.username}"
        WITH RECIPIENT "{value.json.email}"

Embed images (a logo, a chart) directly in the email:

DEFINE ROUTE ReportEmail WITH TYPE EMAIL
    ADD SMTP_CONFIG
        WITH HOST "smtp.company.com"
        WITH PORT '587'
        WITH USERNAME "reports@company.com"
        WITH PASSWORD "password"
        WITH USE_TLS "true"
    ADD EVENT sendReport
        WITH SOURCE_TOPIC "reports/daily"
        WITH TEMPLATE_PATH "/templates/daily_report.html"
        WITH SUBJECT "Daily Report - {value.json.date}"
        WITH RECIPIENT "management@company.com"
        WITH EMBED_RESOURCES
            ADD "/images/logo.png"
            ADD "/images/chart.png"

For Gmail, use an App Password instead of your regular password. Enable 2FA on your Google account first.

SMTP Configuration

The SMTP_CONFIG block tells the route which mail server to send through and how to authenticate.

Server Settings

HOST

string

required

SMTP server address (e.g., smtp.gmail.com, smtp.office365.com).

PORT

integer

required

SMTP port (typically 587 for TLS, 465 for SSL).

USE_TLS

boolean

Enable TLS encryption. Recommended: true.

Authentication

USERNAME

string

required

Email account to send from.

PASSWORD

string

required

Email password or app-specific password.

Event Configuration

Each ADD EVENT block defines a trigger topic and the content of the email it sends.

Trigger & Routing

SOURCE_TOPIC

string

MQTT topic to trigger email sending.

DESTINATION_TOPIC

string

MQTT topic to publish send status.

Email Content

TEMPLATE_PATH

string

Path to HTML email template file.

SUBJECT

string

Email subject line (supports placeholders).

RECIPIENT

string

Email recipient address (supports placeholders).

Template Placeholders

Subjects, recipients, and templates support placeholders that are filled in from the triggering message:

Placeholder	Description
`{value}`	Full JSON payload as string
`{value.json.field}`	Single field from JSON
`{value.json.nested.field}`	Nested field access

Troubleshooting

Email Not Sending

Verify SMTP credentials are correct
For Gmail, ensure you’re using an App Password
Check firewall allows outbound SMTP connections
Verify recipient email address is valid

Email Authentication Failed

Double-check USERNAME and PASSWORD
Ensure 2FA is enabled if using app passwords
Some providers require enabling “less secure apps” access
Check for account lockouts due to failed attempts

Next Steps

MQTT Bridge

Sync topics between two MQTT brokers.

Data Storage Routes

Store MQTT data in databases.

​Email Overview

​When to use it

​Quick Start

​SMTP Configuration

​Event Configuration

​Template Placeholders

​Troubleshooting

​Next Steps

MQTT Bridge

Data Storage Routes

Email Overview

When to use it

Quick Start

SMTP Configuration

Event Configuration

Template Placeholders

Troubleshooting

Next Steps