How to set dynamic email subject and content in Magento 2

Sometimes we need to show customer name, order id, OTP etc in email subject or body.

Here we will use the following Webkul Hello module to implement this blog.

Step 1 -> Register template in email. Webkul/Hello/etc/email_templates.xml

<?xml version="1.0"?>
<!--
/**
 * Webkul Software.
 *
 * @category  Webkul
 * @package   Webkul_Marketplace
 * @author    Webkul
 * @copyright Copyright (c) Webkul Software Private Limited (https://webkul.com)
 * @license   https://store.webkul.com/license.html
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Email:etc/email_templates.xsd">
    <template id="hello_template" label="Hello World" file="hello.html" type="html" module="Webkul_Hello" area="frontend"/>
</config>

Step 2 -> Load email content in Webkul/Hello/view/frontend/email/hello.html

<!--
/**
 * Webkul Software.
 *
 * @category  Webkul
 * @package   Webkul_Marketplace
 * @author    Webkul
 * @copyright Copyright (c) Webkul Software Private Limited (https://webkul.com)
 * @license   https://store.webkul.com/license.html
 */
-->
<!--@subject {{trans "Customer has uploaded attachment on %order_id" order_id=$orderId }} @-->
<!--@styles
body,td { color:#2f2f2f; font:11px/1.35em Verdana, Arial, Helvetica, sans-serif; }
@-->
{{template config_path="design/email/header_template"}}
<table cellspacing="0" cellpadding="0" border="0" width="100%">
    <tr>
        <td align="center" valign="top" style="padding:20px 0 20px 0">
            <table bgcolor="#FFFFFF" cellspacing="0" cellpadding="10" border="0" width="650" style="border:1px solid #E0E0E0;">
                <tr>
                    <td valign="top">
                        <h1 style="font-size:22px;font-weight:normal;line-height:22px;margin:0 0 11px 0;">{{trans "Hello"}},</h1>
                    </td>
                </tr>
                <tr>
                    <td>
                        <table cellspacing="0" cellpadding="0" border="0" width="650">
                            <tbody>
                                <tr>
                                    <td colspan="2" valign="top" style="font-size:24px;padding:7px 9px 9px 9px;border:1px solid #EAEAEA;">
                                            <b>{{trans "Order Id: "}}{{var orderId}}</b>
                                    </td>
                                </tr>
                                <tr>
                                    <td colspan="2" valign="top" style="font-size:12px;padding:7px 9px 9px 9px;border:1px solid #EAEAEA;">
                                        {{trans "A Customer %customer_name has uploaded attachment in order %order_id" customer_name=$customer_name order_id=$orderId}}
                                    </td>
                                </tr>
                            </tbody>
                        </table>
                    </td>
                </tr>
                <tr>
                    <td bgcolor="#EAEAEA" align="center" style="background:#EAEAEA;text-align:center;">
                        <center>
                            <p style="font-size:12px;margin:0;">
                                <strong>{{trans "Thank you"}}</strong>
                            </p>
                        </center>
                    </td>
                </tr>
            </table>
        </td>
    </tr>
</table>
{{template config_path="design/email/footer_template"}}

Step 3 -> Load template with dynamic variables and send mail.

/**
 * Webkul Software.
 *
 * @category  Webkul
 * @package   Webkul_Marketplace
 * @author    Webkul
 * @copyright Copyright (c) Webkul Software Private Limited (https://webkul.com)
 * @license   https://store.webkul.com/license.html
 */
/** @var $storeManager \Magento\Store\Model\StoreManagerInterface $storeManager **/
/** @var $transportBuilder \Magento\Framework\Mail\Template\TransportBuilder **/
/** @var $inlineTranslation \Magento\Framework\Translate\Inline\StateInterface **/
$templateOptions = [
    'area' => \Magento\Framework\App\Area::AREA_FRONTEND,
    'store' => $storeManager->getStore()->getId()
];
$templateVars =  [
    'orderId' => "#00000009",
    'customer_name' => "Share Khan"
];
$from = ['email' => "rastcdex.754@gmail.com", 'name' => 'Admin'];
$inlineTranslation->suspend();
$to = ['dexona.754@gmail.com'];
$transport = $transportBuilder->setTemplateIdentifier('hello_template')
                ->setTemplateOptions($templateOptions)
                ->setTemplateVars($templateVars)
                ->setFrom($from)
                ->addTo($to)
                ->getTransport();
$transport->sendMessage();
$inlineTranslation->resume();

Thanks 🙂