SendGrid php email not working on Azure - php

Question

I'm setting up an Azure-based site that requires an automated email response. As Azure does not natively allow this, I've tried using SendGrid. The code (based on their samples) works perfectly well on my own server (it returns the 202 status and the email is delivered), but not at all on Azure. Is there any known reason for this?
My code is as follows:
<?php
require ("sendgrid-php/sendgrid-php.php");
$from = new SendGrid\Email("DX PHP Test", "MY EMAIL ADDRESS");
$subject = "Sending with SendGrid is Fun";
$to = new SendGrid\Email("Dorian", "MY EMAIL ADDRESS");
$content = new SendGrid\Content("text/plain", "and easy to do anywhere, even with PHP");
$mail = new SendGrid\Mail($from, $subject, $to, $content);
$apiKey = "MY API KEY";
$sg = new \SendGrid($apiKey);
$response = $sg->client->mail()->send()->post($mail);
echo $response->statusCode();
?>
Obviously, I've included the proper API key and email addresses in my working version. The sendgrid-php folder has also been uploaded to the correct place and, as I said earlier, it works on my own server.
I've had a look around but can't find any responses that specifically answer this question. If this approach cannot work for some reason (and I'd like to know why!) can anyone suggest a different approach?
EDIT: The possible duplicate suggested doesn't work either! My SendGrid name and/or password were not recognised when I tried to use it. However, the instructions at this blog do actually work. This is what I did:
Set up a SendGrid account in Azure and note the username generated on the Configurations blade. The password is the same as the one you set the SendGrid account up with.
Download PHPMailer from Github and extract the PHPMailer-master folder to the same folder as the code you want to run.
Use the following code (edited slightly from the blog mentioned above) to send an email from Azure. Obviously, change the username and password to the ones from step 1 above. You'll also need to add a proper email address in the line that begins with '$mail->addAddress' to test that it works:
<?php
require 'PHPMailer-master/PHPMailerAutoload.php';
$mail = new PHPMailer;
//$mail->SMTPDebug = 3; // Enable verbose debug output
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host = 'smtp.sendgrid.net'; // Specify main/backup SMTP servers
$mail->SMTPAuth = true; // Enable SMTP authentication
$mail->Username = 'SENDGRID USERNAME'; // SMTP username
$mail->Password = 'SENDGRID PASSWORD'; // SMTP password
$mail->SMTPSecure = 'tls'; // Enable TLS/SSL encryption
$mail->Port = 587; // TCP port to connect to
$mail->From = 'email#contoso.com';
$mail->FromName = 'From SendGrid website';
$mail->addAddress('TEST EMAIL ADDRESS', 'A NAME'); // Add a recipient
$mail->WordWrap = 50; // Set word wrap to 50 characters
$mail->isHTML(true); // Set email format to HTML
$mail->Subject = 'Here is the subject';
$mail->Body = 'This is the HTML message body <b>in bold!</b>';
if(!$mail->send()) {
echo 'Message could not be sent.';
echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
echo 'Message has been sent';
}
?>