The situation with MVS systems is very  similar to that of VM systems not
running a mailer and RiceMail or  equivalent. You have a thing that comes
with TSO (or TSO/E or whatever)  which generates a certain type of notes,
in Netdata-note format.  This thing (sorry I don't know  the name, I know
it only from  notes I got) does  work with LISTSERV. Then  you have about
200 flavours  of locally-written  or locally-modified  or vendor-supplied
mail systems which all do  things differently, much like locally-enhanced
NOTE EXEC's on VM. These generally don't work.
 
Files from an MVS system not running UCLA-mail or the like generally show
up  as 'userid  OUTPUT'  from SYSTEM@nodeid  (or  #@nodeid, or  something
similar). I  have seen  all imaginable  classes, although  A is  the most
common. If there are Netdata headers, LISTSERV can get a rather good idea
of what the thing  is (mail or file), but if it comes  in PUNCH format it
usually ends up treating it as a file. If you generate RFC822 headers and
can set the NJE filetype to MAIL, your problem will be solved.
 
  Eric