XML Validation of Required Fields of Web service in SOAP Sender - SAP PI 7.5

Is there any way we can validate the XML fields of a SOAP Web service so that the client gets an error message if for example a mandatory field does not contain data and preferably processing is stopped unless they rectify the data?

Currently such messages are failing in PI if this happens but the client still gets a 200 OK. This is an asynchronous scenario so there is no way of validating in backend.

We are on PI 7.5 SP19