Correct Way to Set the From and Reply‑To Headers in PHP Mail

When sending email using PHP’s built‑in mail() function, it’s important to correctly set the From and Reply‑To headers so that mail clients (MUAs) know which address the message is from and where replies should be sent.

Below is a simple and correct example of how to define these headers when sending an email using PHP.

<?php
$to      = 'nobody@example.com';
$subject = 'The subject';
$message = 'Hello';

$headers  = "From: webmaster@example.com\r\n";
$headers .= "Reply-To: webmaster@example.com\r\n";
$headers .= "X-Mailer: PHP/" . phpversion();

mail($to, $subject, $message, $headers);
?>
        

Important Notes

• The From address should be a valid mailbox on your domain.
• The Reply‑To address can be the same or a different mailbox.
• Some mail servers require authentication — consider using an SMTP library such as PHPMailer for reliability.
• Ensure your domain has correct SPF, DKIM, and DMARC records for best deliverability.

For more advanced email sending, using SMTP with authentication is recommended over the basic mail() function.