Rebooting the computer should not affect LISTSERV in any way as far as
these messages are concerned. I only see two explanations:
1. The reboot causes the mail server to resubmit these messages somehow.
2. The messages were in hold status (jobh) and you have a script that
renames *.jobh to *.job before restarting LISTSERV.
Or of course they came back from the usenet gateway another time, etc.
LISTSERV should be stopped before a system reboot for a number of reasons
ranging from minor (gives it a chance to checkpoint statistics to disk,
etc) to more important (makes sure no activity is interrupted in the
middle - you could end up with a posting processed twice, once to half of
the members and then once to everyone).
Eric