How can PHP format emails to correctly display special characters like ü and ö?

When sending emails with special characters like ü and ö using PHP, it is important to set the correct character encoding to ensure they display properly. This can be done by setting the Content-Type header to include the charset parameter with the appropriate encoding, such as UTF-8. Additionally, special characters should be properly encoded using functions like utf8_encode() or htmlspecialchars() to prevent any encoding issues.

// Set the content type and character encoding
$headers = "Content-Type: text/plain; charset=UTF-8\r\n";

// Encode special characters in the email body
$message = "Special characters like ü and ö should be properly encoded.";
$message = utf8_encode($message);

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