<?php
$emails = array(
    'verysecretemail@gmail.com',
    'example@example.org',
    'someotheremail@example.com',
);
 
function obfuscate_email($email) {
    $at_position = strpos($email, '@');
    $chop = rand(1, $at_position - 1);
    $mask = str_repeat('*', rand(4, 8));
 
    $partial_address = substr($email, 0, $chop);
    $domain = substr($email, $at_position);
    return $partial_address . $mask . $domain;
}
 
foreach($emails as $email) {
    var_dump(obfuscate_email($email));
}

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