I've been getting a lot of these messages lately (running 1.5e here).
 
I also, in my infinite boredom, was sending a job file to my LISTSERV
containing the following:
 
      //dummy  job  reply-via=mail
               thanks
      //dummy  eoj
 
I sent this as mail to LISTSERV, and it responded correctly, but just
before I got the PUN FILE 8784 FROM MAILER NOHOLD blahblah, I got a
msg from Listserv saying that "* File 8782 from MAILER@CMUCCVMA
transferred to MS5U@CMUCCVMA", a file which never appeared in my rdr.
 
I've seen, as I said, a few of these messages appear at me for no good
explanation.  Anyone got a suggestion or two?
 
--Marc