Sending email in PHP using Smtp API

<?php

$send_data = [
    "from" => "hello@your-company.com",
    "to" => "Doe.Jhon@gmail.com,contact@global-travel.com",
    "subject" => "New live training session",
    "cc" => "cc_user@example.com",
    "bcc" => "bcc_user@example.com",
    "content" => "Dear partner,\n We are delighted to invite you to an exclusive training session on UX Design. This session is designed to provide essential insights and practical strategies to enhance your skills.",
    "html_content" => "Dear partner,<br />We are delighted to invite you to an exclusive training session on <strong>UX Design</strong>. This session is designed to provide essential insights and practical strategies to enhance your skills."
];

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, 'https://api.turbo-smtp.com/api/v2/mail/send');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($send_data));

$headers = array();
$headers[] = 'Accept: application/json';
$headers[] = 'Consumerkey: <CONSUMER_KEY>';
$headers[] = 'Consumersecret: <CONSUMER_SECRET>';
$headers[] = 'Content-Type: application/json';
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$result = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);

if (curl_errno($ch)) {
    echo 'Error:' . curl_error($ch);
} else if ($http_code !== 200) {
    echo "Request error: ".$http_code;
} else {
    echo "Response: ".$result;
}
curl_close($ch);