Sasidhar, when an incoming email comes , it first reaches the inbox of a specified mail account ( say [email protected] ) . Email listeners monitors the folder of the email inbox ( or any other folder )  for regular basis to check incoming email. This folder name can be specified in the Properties tab under folder name field of the email listener rule form.

Now how you process your incoming email that is something PRPC cant control . You need to take care of it from the email client prospective. For example if your email account is hosted in outlook then you need to follow the steps given in this outlook help material : Manage email messages by using rules - Outlook

You will find similar features for lotus notes, gmail. etc as well online.

Hope this explanation clarifies your doubt.