Hi,
First of all, I am not clear what is your source/sender system(trigger) for your scenario and what adapter you are using for sender and what you will be doing with source system data, since you haven't mentioned anything about sender system. The reason I am saying is that, you can use HTTP sender adapter with HTTP GET method to read http resource response and then transform for IDOC or email based on your requirement condition.
Explain the complete flow
//BR,
Praveen Gujjeti