Send an email programmatically in wordpress with wp_mail using the woocommerce transaction emails template.

emails.php

<?php

// Define a constant to use with html emails
define("HTML_EMAIL_HEADERS", array('Content-Type: text/html; charset=UTF-8'));

// @email - Email address of the reciever
// @subject - Subject of the email
// @heading - Heading to place inside of the woocommerce template
// @message - Body content (can be HTML)
function send_email_woocommerce_style($email, $subject, $heading, $message) {

  // Get woocommerce mailer from instance
  $mailer = WC()->mailer();

  // Wrap message using woocommerce html email template
  $wrapped_message = $mailer->wrap_message($heading, $message);

  // Create new WC_Email instance
  $wc_email = new WC_Email;

  // Style the wrapped message with woocommerce inline styles
  $html_message = $wc_email->style_inline($wrapped_message);

  // Send the email using wordpress mail function
  $mailer->send( $email, $subject, $html_message, HTML_EMAIL_HEADERS );

}

?>

This filled in the missing piece for me — inline styles.
Thank you!!

Thank you for sharing.