如何在Linux系统中通过PHP脚本实现邮件发送功能

<?php
$to = "recipient@example.com"; // 收件人邮箱地址
$subject = "Test Email"; // 邮件主题
$message = "This is a test email."; // 邮件内容

$headers = "From: sender@example.com" . "
"; // 发件人邮箱地址

// 使用PHP的mail()函数发送邮件
if (mail($to, $subject, $message, $headers)) {
    echo "Email sent successfully.";
} else {
    echo "Email sending failed.";
}
?>

<?php
$to = "recipient@example.com"; // 收件人邮箱地址
$subject = "Test Email"; // 邮件主题
$message = "This is a test email."; // 邮件内容

$headers = "From: sender@example.com" . "
"; // 发件人邮箱地址

// 配置SMTP服务器的身份验证信息
ini_set("SMTP", "smtp.example.com");
ini_set("smtp_port", "587");
ini_set("auth_username", "sender@example.com");
ini_set("auth_passWord", "password");

// 使用PHP的mail()函数发送邮件
if (mail($to, $subject, $message, $headers)) {
    echo "Email sent successfully.";
} else {
    echo "Email sending failed.";
}
?>