It's not such easy to find out a right Exchange server nowerdays. Starting with Exchange 2007 you clients connects to a CAS or Mailbox Server which may or may not be colocated with a HUB server which has an SMTP instance running. In addition the HUB server may reject SMTP mail due to security. The best way would be to ask your Exchange admin what is the best way to send Emails from your application.
I would also prefer not to use Outlook if don't have to. Using a usual SMTP mail module allows you to run the application without Outlook installed and maybe even move to another operating system without rewriting the application. And there is one error source less in the process.