refference: https://github.com/sendgrid/sendgrid-php

install

$ composer install sendgrid/sendgrid

set api key

echo "export SENDGRID_API_KEY='YOUR_API_KEY'" > sendgrid.env
echo "sendgrid.env" >> .gitignore
source ./sendgrid.env

sample code

see: https://github.com/sendgrid/sendgrid-php/blob/master/examples/contactdb/contactdb.php

<?php
require 'vendor/autoload.php';

$apiKey = getenv('SENDGRID_API_KEY');
$sg = new \SendGrid($apiKey);

$response = $sg->client->contactdb()->lists()->get();
echo 'status code: ', $response->statusCode(), PHP_EOL;
echo '======body======',PHP_EOL;
var_dump($response->body());
echo '======headers======',PHP_EOL;
var_dump($response->headers());