If the Auto Import option in your POST API token settings is disabled then the incoming POST data is not imported into the CRM directly. Instead, it is displayed on the Incoming POST Data page where you can preview the data and decide whether to import it into the CRM or reject it. 

To manage your incoming POST Data navigate to Manage > Administration > POST API > Manage Incoming POST Data, select the desired date range, and click Search:

To view the incoming data for a specific lead, click on the triangle icon in the Data column.

The data report now shows the information that will be imported to lead mapped lead fields, as well as the entire content of the POST API message:

If you wish to map additional fields from the POST API message (which were not already mapped in the POST Token settings) you can do so by clicking on the Map Field button, and selecting a lead field to map to:

To import or to delete the incoming data, select the leads and hit the Delete Selected or the Import Selected Leads button: 

Use the Export button near the Search box to export the data for selected leads to a CSV or an Excel file: