How can I receive xml via as2 without having a defined xml doctype

I have a trading partner that sends us pdfs, csv and xml files. i have a User Process Payload Service defined so if web methods cant figure out the doctype then it uses that service. This is how the csv and pdfs are working. The problem with the xml is the partner has a process that generates the xml on the fly so they dont have a schema to send me so I can define a xml doctype from MWS. When the AS2 EDIINT comes into IS the wm.EDIINT.rules:processMsg is called and it sees the payload as application/xml so it tries to find the doc type that matches that. The trading partner cant change the payload type and cant give me a schema. Is there anything else i can do?

You can ask your client to send xml without using content-type=application/xml.
They can use for example: text/xml, so it won’t trigger the default process. it will end up reaching your User Process Payload Service. You handle it there in whatever way you want.