<?php

// get sendgrid
$sendgrid = new \SendGrid('MY_KEY');

// create sender and recipient
$from = new SendGrid\Email('App name', 'no-reply@app-name.com');
$to = new SendGrid\Email('Users name', 'user@user.com');

// create subject and content
$subject = 'Email title';
$content = new SendGrid\Content('text/plain', 'Test content');

// create email
$mail = new SendGrid\Mail($from, $subject, $to, $content);

// send email
$result = $sendgrid->client->mail()->send()->post($mail);

SendGrid\Response Object
(
    [statusCode:protected] => 0
    [body:protected] => 
    [headers:protected] => Array
        (
            [0] => 
        )
)