我对 CakePHP 了解不多，但 Sendgrid 提供了一种简单的方法，可以在 php 中将单个邮件发送给多个收件人，您可以将此代码转换为 Cakephp，
Sendgrid 提供了Mail::addTos一种方法，我们可以在其中添加多个要向其发送邮件的邮件，
我们必须将用户电子邮件和用户名的关联数组传递到addTos.
见下面的例子：
$tos = [
//user emails => user names
"user1@example.com" => "Example User1",
"user2@example.com" => "Example User2",
"user3@example.com" => "Example User3"
];
$email->addTos($tos);
如果您想查看 sendgrid-php github 库中提供的完整示例，那么我将其包含在下面，因此您可以理解整个示例：
<?php
require 'vendor/autoload.php'; // If you're using Composer (recommended)
// Comment out the above line if not using Composer
// require("<PATH TO>/sendgrid-php.php");
// If not using Composer, uncomment the above line and
// download sendgrid-php.zip from the latest release here,
// replacing <PATH TO> with the path to the sendgrid-php.php file,
// which is included in the download:
// https://github.com/sendgrid/sendgrid-php/releases
$email = new \SendGrid\Mail\Mail();
$email->setFrom("test@example.com", "Example User");
$tos = [
"test+test1@example.com" => "Example User1",
"test+test2@example.com" => "Example User2",
"test+test3@example.com" => "Example User3"
];
$email->addTos($tos);
$email->setSubject("Sending with Twilio SendGrid is Fun");
$email->addContent("text/plain", "and easy to do anywhere, even with PHP");
$email->addContent(
"text/html", "<strong>and easy to do anywhere, even with PHP</strong>"
);
$sendgrid = new \SendGrid(getenv('SENDGRID_API_KEY'));
try {
$response = $sendgrid->send($email);
print $response->statusCode() . "\n";
print_r($response->headers());
print $response->body() . "\n";
} catch (Exception $e) {
echo 'Caught exception: '. $e->getMessage(). "\n";
}