My guess is that userid ROOT@ is trying to e-mail the OWNER- list
address via a MAILER, and LISTSERV is rejecting such since ROOT
is probably a reserved userid that is disallowed from mailing to
lists or LISTSERV, the purpose being the preemption of e-mail
loops.
 
Thus there is probably a subscriber at the ROOT@host site (or
subdomain) that is no longer able to receive e-mail (either
directly from your list, or via possibly an autoforward
mechanism).
 
/Pete Weiss at Penn State