What considerations should be made when handling email addresses with special characters in both the local part and domain part using PHP functions like idn_to_ascii()?

When handling email addresses with special characters in both the local part and domain part, it is important to normalize and convert these special characters to ASCII using functions like idn_to_ascii(). This ensures that the email address is in a standardized format that can be properly processed by email systems. By converting special characters to ASCII, you avoid potential encoding issues and ensure the email address is valid and can be used reliably.

$email = "üser@example.com";
list($localPart, $domainPart) = explode('@', $email);

$normalizedEmail = idn_to_ascii($localPart) . '@' . idn_to_ascii($domainPart);

echo $normalizedEmail;