HOW TO get notification when SMTP mails are received

Question

hi, Need to setup a SMTP server within my C# server application to be able to receive incoming email message from other email exchange server. We are not using any post office (no POP3, no IMAP etc) Right now, we have figured out that we can config the server to automatically store the received mail to some local folder. Then we need to read the mail from that location. The problem now is: How can we be notified when there is new mail?? Is polling the only way? I've read some low-level stuff about IIS events/sinks (deep stuff) eg. IIS OnSubmission event versus CDONT's CDO_OnArrival event. Cannot seem to make sense of that stuff. Can that be used to do the notification? Any code samples? Any help or thots wd be greatly appreciated soonest!!! ThanksSS!