This Tutorial is to show you how to send an email message with HTML page or image inside.

Prerequisites

Message flow

Like a start point we will use Generator that will imitate regular rule chain messages flow: prepared message and metadata where we can contain some dynamic field for to email node.
The To email node prepares data, destination email, and other for email message.
The Send email node sends a message.

Configuring Rule Nodes

Configuring “to email” node

At first, lets create and configure “to email” node.

Go to rule chain, find to email node and drag it to the canvas.
Specify: Name, From Template, To Template - we will use pattern to find an email in data of message, Subject Template. Select Mail Body Type HTML or Dynamic. We will use the Dynamic.
Specify HTML to Body Template (you can use our example).
Press Add.

Example of HTML page

Example of HTML with image

Example of HTML

<table class="main" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 14px; box-sizing: border-box; border-radius: 3px; width: 100%; background-color: #f6f6f6; margin: 0px auto;" cellspacing="0" cellpadding="0" bgcolor="#f6f6f6">
    <tbody>
    <tr style="box-sizing: border-box; margin: 0px;">
        <td class="content-wrap" style="box-sizing: border-box; vertical-align: top; margin: 0px; padding: 20px;" align="center" valign="top">
            <table style="box-sizing: border-box; border: solid 1px #e9e9e9; border-radius: 3px; margin: 0px; height: 127px; padding: 20px; background-color: #ffffff; width: 600px; max-width: 600px !important;" width="600" cellspacing="0" cellpadding="0">
                <tbody>
                <tr style="box-sizing: border-box; margin: 0px;">
                    <td class="content-block" style="color: #348eda; box-sizing: border-box; border-radius: 6px; vertical-align: top; margin: 0px; padding: 0px 0px 20px; width: 839px;" valign="top">
                        <h2>Test message using 'to email' rule node</h2>
                    </td>
                </tr>
                <tr style="box-sizing: border-box; margin: 0px;">
                    <td class="content-block" style="box-sizing: border-box; vertical-align: top; margin: 0px; padding: 0px 0px 20px; width: 600px;" valign="top"><span style="color: #000000;">This email is indicating that your outgoing mail settings were set up correctly.</span></td>
                </tr>
                <tr style="box-sizing: border-box; margin: 0px;">
                    <td class="content-block" style="box-sizing: border-box; vertical-align: top; margin: 0px; padding: 0px 0px 20px; width: 600px;" valign="top"><span style="color: #000000;">&mdash; The ThingsBoard :)</span></td>
                </tr>
                </tbody>
            </table>
        </td>
    </tr>
    </tbody>
</table>

To send an image, you just need to specify the name of the image with the file extension.

Example of HTML with image

<img src="cid:tb.example.png" />

Configuring generator

At the second stage, let’s configure the “generator” node:

Find in the Rule Chain Generator and drag it to the canvas
Specify name field, choose “1” for message count and, for example “2” for Period in seconds
Now we need to prepare JS code, also you can use our example.

Here we need to specify fields in metadata, that are dynamic in “to email” node. In our example it is “isHtml” and “userEmail” fields.

JS code for HTML page

JS code for image

Example of generator JS code

var metadata = { userEmail: 'info@thingsboard.org', isHtml: true };
var msgType = "POST_TELEMETRY_REQUEST";
return { msg: {}, metadata: metadata, msgType: msgType }

To send an image you need to encode the image to Base64. To do this you need to find some service that can do this and set the result string for encodedImage in the next example.

Example of generator JS code

var encodedImage = 'HERE_YOU_BASE_64_ENCODED_IMAGE';
var images = {
    "tb.example.png": encodedImage
};
var metadata = { 
    userEmail: 'info@thingsboard.org', 
    images: JSON.stringify(images), 
    isHtml: true 
};
var msgType = "POST_TELEMETRY_REQUEST";
return { msg: {}, metadata: metadata, msgType: msgType }