If you are using Fax forwarding to Email feature, where you setup incoming fax to be forwarded to an email address, you are using the Job workflow sheet and the priting of every fax is a behaviour setup in this job sheet. Just as Enea advised.
If you are using any other application to manage incoming faxes, please let us know which and how its setup.
We have the fax to scan set up and it works well. We want to discontinue the automatic printing of the faxes that come in. How do I turn that off?