WordPress添加评论回复邮件提醒通知功能

function comment_mail_notify($comment_id) {
 $admin_notify = '1'; // admin 要不要收回复通知 ( '1'=要 ; '0'=不要 )
 $admin_email = get_bloginfo ('admin_email'); // $admin_email 可改为你指定的 e-mail.
 $comment = get_comment($comment_id);
 $comment_author_email = trim($comment->comment_author_email);
 $parent_id = $comment->comment_parent ? $comment->comment_parent : '';
 global $wpdb;
 if ($wpdb->query("Describe {$wpdb->comments} comment_mail_notify") == '')
 $wpdb->query("ALTER TABLE {$wpdb->comments} ADD COLUMN comment_mail_notify TINYINT NOT NULL DEFAULT 0;");
 if (($comment_author_email != $admin_email && isset($_POST['comment_mail_notify'])) || ($comment_author_email == $admin_email && $admin_notify == '1'))
 $wpdb->query("UPDATE {$wpdb->comments} SET comment_mail_notify='1' WHERE comment_ID='$comment_id'");
 $notify = $parent_id ? get_comment($parent_id)->comment_mail_notify : '0';
 $spam_confirmed = $comment->comment_approved;
 if ($parent_id != '' && $spam_confirmed != 'spam' && $notify == '1') {
 $wp_email = 'no-reply@' . preg_replace('#^www.#', '', strtolower($_SERVER['SERVER_NAME'])); // e-mail 发出点, no-reply 可改为可用的 e-mail.
 $to = trim(get_comment($parent_id)->comment_author_email);
 $subject = '您在 [' . get_option("blogname") . '] 的留言有了回复';
 $message = '
 <div>
 <p>' . trim(get_comment($parent_id)->comment_author) . '，您好!</p>
 <p>您曾在《' . get_the_title($comment->comment_post_ID) . '》的留言：<br /><br />'
 . trim(get_comment($parent_id)->comment_content) . '</p>
 <p>' . trim($comment->comment_author) . ' 给您的回复：<br /><br />'
 . trim($comment->comment_content) . '</p>
 <p>您可以点击 <a href="' . htmlspecialchars(get_comment_link($comment->comment_parent)). '" target="_blank">查看回复的完整內容</a></p>
 <p>感谢您对 <a href="' . get_option('home') . '" target="_blank">' . get_option('blogname') . '</a> 的关注，如您有任何疑问，欢迎在博客留言。</p>
 <p>(此邮件由系统自动发送，请勿回复。)</p>
 </div>';
 $from = "From: \"" . get_option('blogname') . "\" <$wp_email>";
 $headers = "$from\nContent-Type: text/html; charset=" . get_option('blog_charset') . "\n";
 wp_mail( $to, $subject, $message, $headers );
 }
}
add_action('comment_post', 'comment_mail_notify');
 
/* 自动加勾选栏 */
function add_checkbox() {
 echo '<input type="checkbox" name="comment_mail_notify" id="comment_mail_notify" value="comment_mail_notify" checked="checked" style="margin-left:20px;" /><label for="comment_mail_notify">有人回复时邮件通知我</label>';
}
add_action('comment_form', 'add_checkbox');