title: SmtpClient.SendAsync bug in ASP.NET 2.0
body: <p>I may be wrong, but if you are working with SmtpClient.SendAsync in ASP.NET 
  2.0 and it throws an exception, the thread processing the request waits 
  indefinitely for the operation to complete.</p>
  
  <p>To reproduce this problem, simply use an invalid SMTP address for the host 
  that could not be resolved when sending an email.</p>
  
  <p>Note that you should set Page.Async = true to use SendAsync.</p>
  
  <p>If Page.Async is set to false and Send throws an exception the thread 
  does not block, and the page is processed correctly.</p>
  
  <p>TIA.</p>