What steps can be taken to troubleshoot and resolve PHP mail delivery issues, especially when emails are not reaching specific email addresses?

When emails sent via PHP are not reaching specific email addresses, it could be due to various reasons such as incorrect email configurations, server issues, or the emails being marked as spam. To troubleshoot and resolve this issue, you can check the email logs on the server, ensure that the email addresses are correct, and verify that the email server is properly configured.

// Example PHP code snippet to troubleshoot and resolve email delivery issues
// Check email logs on the server
// Make sure email addresses are correct
// Verify email server configuration

// Example code to send an email
$to = 'recipient@example.com';
$subject = 'Test Email';
$message = 'This is a test email sent from PHP.';
$headers = 'From: sender@example.com';

// Send email
$mail_sent = mail($to, $subject, $message, $headers);

if ($mail_sent) {
    echo 'Email sent successfully.';
} else {
    echo 'Failed to send email.';
}