User Authentication is not mandatory but If your Web service requires logon data, select the Configure User Authentication checkbox and fill in the corresponding fields.
If the Web service is outside your system landscape and you need to address a proxy
server, select the Configure Proxy checkbox.
The sender SOAP adapter does not require a SOAP action, but you always have
to apply logon data when using the SOAP adapter. In the central adapter engine
you can use a service user such as xiappluser; in a non-central adapter
engine or a PCK you must use one of the user names assigned to security role
xi_adapter_soap_message for component XISOAPAdapter.