What headers should be included when sending emails in PHP to ensure proper delivery and handling of responses?

When sending emails in PHP, it is important to include certain headers to ensure proper delivery and handling of responses. Some essential headers to include are the "From" header to specify the sender's email address, the "Reply-To" header to specify the email address where responses should be directed, and the "Content-Type" header to specify the type of content being sent (e.g., text/plain or text/html).

$to = "recipient@example.com";
$subject = "Your subject here";
$message = "Your message here";

$headers = "From: sender@example.com\r\n";
$headers .= "Reply-To: replyto@example.com\r\n";
$headers .= "Content-Type: text/html\r\n";

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