In this document: Step 2 of 3: Create a Salesforce User for Marketo (Enterprise/Unlimited) - Marketo Docs
There is a link to something called Set Sharing Settings - these are guidelines to customize which Leads/Contacts you want to keep out of Marketo. Unfortunately the link no longer works and search for the title of the document yields no results.
Does anyone have this document?
Does anyone know what settings are necessary to prevent any leads created in SFDC to NOT synch back to Marketo.
You can do a number of things.