I think the best and easiest way to implement a global SUSPEND and
RESUME would be (as has already been suggested) to do it at the local
user level:  Provide a trivial exec for signup/signoff/suspend/resume
that keeps track of all the lists in a file in the local user's
directory when it sends off the corresponding LISTSERV commands.  I
already use a TSO clist for signup:  "SIGNUP listname host".  This is
shorter than the actual commands, and it also does a SET REPRO for me.
 
/Leonard