// Created on savesnippets.com · https://savesnippets.com/vewCbt5JIJdFy6
<?php
function obfuscateEmail(string $email): string {
    $safe = '';
    foreach (str_split($email) as $c) {
        $safe .= rand(0, 1)
            ? '&#' . ord($c) . ';'
            : '&#x' . dechex(ord($c)) . ';';
    }
    return '<a href="mailto:' . $safe . '">' . $safe . '</a>';
}

echo obfuscateEmail('hello@example.com');
// <a href="mailto:&#x68;&#101;...">&#x68;&#101;...</a>
//
// Renders as "hello@example.com" in browsers but most regex-based
// scrapers won't recognize it.