Using Postal on Azure with Sendgrid

Hi, i'm trying to use Postal on a web app hosted in Azure. But get this error:
System.IO.IOException: Unable to read data from the transport connection: net_io_connectionclosed.

**This is the code i'm using:**

dynamic email = new Email("Test");
email.To = "myEmail@gmail.com";
System.Net.NetworkCredential credentials = new System.Net.NetworkCredential("azure_d3e************************_b5e@azure.com", "7N**_********5C");
SmtpClient smtpClient = new SmtpClient("smtp.sendgrid.net", Convert.ToInt32(587));
smtpClient.Credentials = credentials;
email.Send();

**My Test view:**

To: myEmail@gmail.com
From: test@test.com
Subject: Important Message

Hello,
This is a tests!!

**My web.config smtp settings:**