Sending custom emails in WordPress. Visit blog post https://bit.ly/2xlZG9L

send_email_functions.php

<?php

  /**
    $email_custom_data = array(
      'title'              => '',
      'content'            => '',
      'logo_url'           => '',
      'featured_image_url' => '',
      'cta_button_url'     => '',
      'cta_button_text'    => '',
    )
  */
  function compose_email(array $email_custom_data, string $email_address = '') {

    // If we don't have an email passed then the user must be logged in.
    if (!$email_address) {

      $user = get_current_user_id();

      if (!$user) {
        return false;
      }

      $curr_user     = get_userdata(get_current_user_id());
      $email_address = $curr_user->data->user_email;
    }

    foreach ($email_custom_data as $key => $value) {
      $email_custom_data[$key] = html_entity_decode($value);
    }

    // Generate our email template and apply all the data from $email_custom_data.
    ob_start();
    include_once 'send_email_template.php';
    $email_to       = $email_address;
    $email_subject  = $email_custom_data['title'];
    $email_headers  = ['From: Company Name <donotrespond@companyname.com>', 'Cc: support@companyname.com'];
    $email_body     = ob_get_contents();
    ob_get_clean();

    // Send an email using the wp_mail() function.
    if (!wp_mail($email_to, $email_subject, $email_body, $email_headers)) {
      return false;
    }

    return true;
  }

  function overwrite_email(array $email_data, array $email_custom_data) {
    
    foreach ($email_custom_data as $key => $value) {
      $email_custom_data[$key] = html_entity_decode($value);
    }

    // Generate our email template and apply all the data from $email_custom_data.
    ob_start();
    include_once 'send_email_template.php';
    $email_data['subject']  = $email_custom_data['title'];
    $email_data['headers']  = ['From: Company Name <donotrespond@companyname.com>', 'Cc: support@companyname.com'];
    $email_data['message']  = ob_get_contents();
    ob_get_clean();

    return $email_data;
  }