Map all input variables will automatically map the values of process variables to values or variables within a model if their names are identical. Outputs are not mapped at all, so there will be no transfer of data from the model, back to process variables.
For example, if Map all input variables is selected for an instance of the email service, process variables named to, subject and text can be used to automatically set the values for the recipient, subject and message in the connector. No output variables are required to be sent back to the process as the execution of the email service is always treated as successful.