Does janusSEAL for Outlook create Internet message header extension (X-Protective-Marking) protective markings that comply with the Email Protective Marking Standard for the Australian Government?

Yes. In the ABNF syntax used by the standard, janusSEAL products can create X-header forms according to:

  protective-mark-short-form        = classification              ; as defined in
                                                                  ; AGIMO Protective
                                                                  ; Marking standard  
  jS-2-protective-mark-medium-form  = protective-mark-short-form     
  jS-2-protective-mark-long-form    = version
                                        comma-FWS namespace
                                        comma-FWS jS-2-protective-mark-medium-form
                                        comma-FWS origin
  jS-2-protective-marked-header     = "X-Protective-Marking:"
                                        [FWS] jS-2-protective-mark-long-form
                                        [FWS] CRLF