composer require mrprompt/silex-sendgrid

use SilexFriends\SendGrid\SendGrid as SendGridServiceProvider;

$app->register(
    new SendGridServiceProvider(
        $api_name,
        $api_key
    )
);

$app['sendgrid'](
    'foo@bar.bar', // to
    'noreply@foobar', // from
    'template-name', // template name
    ['name' => ['Foo Bar']] // template tags
);

./vendor/bin/phpunit