title: Exchange server actively refuses my connection
body: <p>I'm writing a ASP.NET application used within our company. Now I want to send emails to some users via a email account on our exchange server.</p>
  
  <p>I tried to use System.Net.Mail.SmtpClient, where a proprietary account and password are given to specify the credentials. But the code failed with following exception:
  "No connection could be made because the target machine actively refused it"</p>
  
  <p>Is that due to Exchange Server policies to prevent spam? How can I get it to work?</p>