I'm planning on creating a simple SMTP Server to auto parse incoming emails to integrate into an application. I chose this method over polling a pop3 account so that I can get instant notification.
Not knowing a whole lot about server protection, I was wondering what I should do to protect against attacks?
The SMTP server will be a .NET app running on Windows Server 2008. My plan is to only allow incoming content, and only emails "to" a whitelist of known email addresses defined within the application.