所以wordpress的核心并没有真正更新unicode域的电子邮件许可。即使是像德语umlauts（äÄöÖÜß）这样的简单特殊字符也不允许出现在名称的域部分。

因此，我一直在考虑向is\\U电子邮件功能添加一个具有高优先级的过滤器，并简单地返回结果。但它似乎并没有像我预期的那样发挥作用。以下是我尝试过的：

// Code written in my themes functions.php
function kk_email_validation_override( $email )
{
    $pattern = \'/^(?!(?:(?:\\\\x22?\\\\x5C[\\\\x00-\\\\x7E]\\\\x22?)|(?:\\\\x22?[^\\\\x5C\\\\x22]\\\\x22?)){255,})(?!(?:(?:\\\\x22?\\\\x5C[\\\\x00-\\\\x7E]\\\\x22?)|(?:\\\\x22?[^\\\\x5C\\\\x22]\\\\x22?)){65,}@)(?:(?:[\\\\x21\\\\x23-\\\\x27\\\\x2A\\\\x2B\\\\x2D\\\\x2F-\\\\x39\\\\x3D\\\\x3F\\\\x5E-\\\\x7E]+)|(?:\\\\x22(?:[\\\\x01-\\\\x08\\\\x0B\\\\x0C\\\\x0E-\\\\x1F\\\\x21\\\\x23-\\\\x5B\\\\x5D-\\\\x7F]|(?:\\\\x5C[\\\\x00-\\\\x7F]))*\\\\x22))(?:\\\\.(?:(?:[\\\\x21\\\\x23-\\\\x27\\\\x2A\\\\x2B\\\\x2D\\\\x2F-\\\\x39\\\\x3D\\\\x3F\\\\x5E-\\\\x7E]+)|(?:\\\\x22(?:[\\\\x01-\\\\x08\\\\x0B\\\\x0C\\\\x0E-\\\\x1F\\\\x21\\\\x23-\\\\x5B\\\\x5D-\\\\x7F]|(?:\\\\x5C[\\\\x00-\\\\x7F]))*\\\\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-+[a-z0-9äÄüÜöÖß]+)*\\\\.){1,126}){1,}(?:(?:[a-z][a-z0-9äÄüÜöÖß]*)|(?:(?:xn--)[a-z0-9äÄüÜöÖß]+))(?:-+[a-z0-9äÄüÜöÖß]+)*)|(?:\\\\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\\\\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\\\\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\\\\]))$/iD\';

    if (preg_match($pattern, $email)) {
        return trim(strtolower($email));
    }

    return false;
}
add_filter(\'is_email\', \'kk_email_validation_override\', 99, 4);

但出于某种原因，最初的wordpressis_email() 仍在通话中。我是否应用了错误的过滤器，或者为了不进入wordpress的过滤链，我还遗漏了什么？

提前感谢！

function my_email_validation( $is_email, $email, $context )
{
    if ( <MY CONDITION> ) {  // check if it is an email
        return true;
    }

    return false;
}
add_filter( \'is_email\', \'my_email_validation\', 99, 3 );