Hello Simonbr,
I searched our online knowledge base and found an article where you can specify trays to receive faxes. You will need to scoll down to the section for Configuring Settings for Fax Paper Output in the Embedded Web Server.
If you're still having issues after trying these steps please consider calling our support department for additional assistance.
When receiving faxes that are of legal size, my Xerox is not selecting the correct paper size, its always on letter. Is there a way to configure it to auto to select either letter or legal?