gistfile1.php

<?php
require('vendor/autoload.php');
$cfg = require('cfg.php'); //returns ['username'=>'???', 'password'=>'???']
$to = 'sgtest_to@mailinator.com';
$cc = 'sgtest_cc@mailinator.com';
$bcc = 'sgtest_bcc@mailinator.com';
$sg = new SendGrid($cfg['username'], $cfg['password']);
$m = (new SendGrid\Email())
    ->addTo($to)
    ->addCc($cc)
    ->addBcc($bcc)
    ->setFrom('sgtest_from@mailinator.com')
    ->setSubject('CC and BCC test')
    ->setText('Test')
    ->setHtml('<p>Test</p>')
    ;   
$response = $sg->send($m);
var_dump($response);