use the return path an existing email created by default. and can select in the email wich is used for it.
By default use an existing email created by default as a return path . Return path should be configured in mail tab instead of solution from here:
This feature request is based on an insufficient use of the PHP mail() function. The mail() function has a fifth parameter by which users can easily set the "from" address (which is referred to as the "return path" in this feature request). If the "from" address is not explicitely set in that PHP function, PHP uses the system user und which it is executed as the mail sender. This is an expected behavior. It is left up to the software developer to fit his application with a suitable configuration option to set a sender address. This is nothing that webspace control panel can dictate. For that reason we must decline this request.