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