title: How to handle bounced emails?
body: <p>The users of my app can send emails to a set of people. Some of the emails might be invalid.
  I need to let the user know which emails bounced.</p>
  
  <p>Is this possible to do? If yes, any pointers will be helpful.</p>
  
  <p>I use .NET, C# to send email. I don't use any third part tools to send mails.</p>
  
  <p>Thanks</p>