Are there any specific PHP functions or libraries that can assist in managing Umlauts in email addresses?

When dealing with email addresses containing Umlauts (such as ä, ö, ü), it's important to normalize and validate the email address to ensure it is correctly formatted and can be processed without issues. One way to handle Umlauts in email addresses is to use the `idn_to_ascii` function in PHP, which converts Internationalized Domain Names (IDN) to the ASCII-compatible encoding known as Punycode. This function can help convert Umlauts and other special characters in the domain part of the email address to a format that is compatible with standard email protocols.

$email = 'müller@example.com';
list($local, $domain) = explode('@', $email);

$ascii_domain = idn_to_ascii($domain);
$normalized_email = $local . '@' . $ascii_domain;

// Validate the normalized email address
if (filter_var($normalized_email, FILTER_VALIDATE_EMAIL)) {
    // Process the email address
    echo 'Normalized email address: ' . $normalized_email;
} else {
    echo 'Invalid email address';
}