What could be the potential reasons for the PHP script not sending emails using sendmail on a Linux server?

The potential reasons for a PHP script not sending emails using sendmail on a Linux server could include misconfigured sendmail settings, firewall restrictions blocking outgoing emails, or incorrect PHP mail function parameters. To troubleshoot, ensure sendmail is properly configured, check firewall settings, and verify the PHP mail function parameters.

// Example PHP code snippet to send an email using sendmail on a Linux server

$to = "recipient@example.com";
$subject = "Test Email";
$message = "This is a test email from PHP using sendmail.";
$headers = "From: sender@example.com";

// Send email using sendmail
if (mail($to, $subject, $message, $headers)) {
    echo "Email sent successfully.";
} else {
    echo "Email sending failed.";
}