<?php

$randomizer = new \Random\Randomizer();

$randEmail = sprintf(
    "%s@%s.com",
    //Select 16 characters from letters and numbers
    $randomizer->getBytesFromString(
        'abcdefghijklmnopqrstuvwxyz0123456789',
        16,
    ),
    //Select 5 characters from letters
    $randomizer->getBytesFromString(
        'abcdefghijklmnopqrstuvwxyz',
        5,
    ),    
);

echo "randEmail is '$randEmail'";