PHP

export SECURESSMTP_API_KEY="qcs_live_..."

<?php
// securessmtp.php (PHP 8.0 or later, needs the curl extension)

function securessmtp_send(array $message): array
{
    $ch = curl_init('https://securessmtp.com/api/v1/mail/send');
    curl_setopt_array($ch, [
        CURLOPT_POST => true,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_HTTPHEADER => [
            'x-securessmtp-api-key: ' . getenv('SECURESSMTP_API_KEY'),
            'Content-Type: application/json',
        ],
        CURLOPT_POSTFIELDS => json_encode($message, JSON_THROW_ON_ERROR),
        CURLOPT_TIMEOUT => 30,
    ]);

    $body = curl_exec($ch);
    if ($body === false) {
        throw new RuntimeException('SecureSMTP: ' . curl_error($ch));
    }
    $status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);

    $result = json_decode($body, true);
    if (!is_array($result) || empty($result['ok'])) {
        $reason = $result['reason'] ?? $result['error'] ?? 'request_failed';
        throw new RuntimeException("SecureSMTP: $reason (HTTP $status)", $status);
    }
    return $result; // ['ok' => true, 'sent' => true, 'mode' => ..., 'message_id' => ...]
}

<?php
require __DIR__ . '/securessmtp.php';

$result = securessmtp_send([
    'to' => '[email protected]',
    'subject' => 'Your order has shipped',
    'html' => '<p>Your order is on its way.</p>',
    'text' => 'Your order is on its way.',
    'from' => ['name' => 'Acme Store'],
    'reply_to' => '[email protected]',
    'attachments' => [[
        'filename' => 'invoice-1042.pdf',
        'content' => base64_encode(file_get_contents(__DIR__ . '/invoice-1042.pdf')),
        'content_type' => 'application/pdf',
    ]],
]);

echo $result['message_id'];

<?php
try {
    securessmtp_send([
        'to' => '[email protected]',
        'subject' => 'Hello',
        'text' => 'Hi there.',
    ]);
} catch (RuntimeException $e) {
    // The message holds the reason, e.g. "SecureSMTP: rate_limited (HTTP 200)".
    // getCode() is the HTTP status (0 for a network error).
    error_log($e->getMessage());
}

<?php
// composer require phpmailer/phpmailer
use PHPMailer\PHPMailer\Exception;
use PHPMailer\PHPMailer\PHPMailer;

require __DIR__ . '/vendor/autoload.php';

$mail = new PHPMailer(true); // true = throw exceptions

try {
    $mail->isSMTP();
    $mail->Host = 'smtp.securessmtp.com';
    $mail->Port = 587;
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS; // or ENCRYPTION_SMTPS with port 465
    $mail->SMTPAuth = true;
    $mail->Username = 'securessmtp';
    $mail->Password = getenv('SECURESSMTP_API_KEY');
    $mail->CharSet = PHPMailer::CHARSET_UTF8;

    $mail->setFrom('[email protected]', 'Acme Store');
    $mail->addAddress('[email protected]');
    $mail->Subject = 'Your order has shipped';
    $mail->isHTML(true);
    $mail->Body = '<p>Your order is on its way.</p>';
    $mail->AltBody = 'Your order is on its way.';
    $mail->addAttachment(__DIR__ . '/invoice-1042.pdf');

    $mail->send();
} catch (Exception $e) {
    error_log('Email failed: ' . $mail->ErrorInfo);
}