如何使用SparkPost PHP API一次发送多封电子邮件？

composer require sparkpost/php-sparkpost

require 'vendor/autoload.php';

use SparkPost\SparkPost;
use GuzzleHttp\Client;
use Http\Adapter\Guzzle6\Client as GuzzleAdapter;

$httpClient = new GuzzleAdapter(new Client());
$sparkpost = new SparkPost($httpClient, ['key' => 'YOUR_API_KEY']);

$emailData = [
    'from' => 'sender@example.com',
    'to' => ['recipient1@example.com', 'recipient2@example.com'],
    'subject' => 'Hello from SparkPost',
    'html' => '<p>This is the HTML content of the email</p>',
    'text' => 'This is the plain text content of the email'
];

$response = $sparkpost->transmissions->sendMany([
    [
        'from' => $emailData['from'],
        'to' => $emailData['to'],
        'subject' => $emailData['subject'],
        'html' => $emailData['html'],
        'text' => $emailData['text']
    ],
    [
        'from' => $emailData['from'],
        'to' => ['recipient3@example.com', 'recipient4@example.com'],
        'subject' => $emailData['subject'],
        'html' => $emailData['html'],
        'text' => $emailData['text']
    ]
]);