The term "served out" in this context means LISTSERV has given up on
 the address in question after receiving numerous invalid commands.
 It either means the person at the indicated address is confused and
 doesn't understand how to send the right commands to LISTSERV, or that
 the mail system on his/her site is sending back a delivery error to
 LISTSERV each time LISTSERV responds to his/her mail.  Since such
 exchanges can result in infinite loops, LISTSERV simply ignores mail
 from an address after it's received a bunch of bad commands.  If you
 think it's just a confused user, then you can have the LISTSERV
 postmaster issue the command,   serve user@node on   to restore their
 LISTSERV access.
 
 -jj