The OK mechanism is somewhat resource intensive when used in large doses.
Nothing to worry about for everyday use,  but the day you do a renewal on
a  list with  500,000 subscribers  (with  500,000 cookies  that will  all
expire at the  same time), things might be different.  I expect that with
1.8c most  people will switch  to passive renewal, which  doesn't require
the recipient  to do  anything to stay  on the list  and also  allows the
elimination  of all  bounces. The  main reason  for using  active renewal
would be to select  users who know the name of the  list they are reading
every  day and  who have  enough technical  skills to  understand how  to
compose a new message  and type the word CONFIRM followed  by the name of
the list. It really depends on the list, for instance if there are people
on THIS list  who don't know what LSTOWN-L  is or how to send  a new mail
message,  I would  view  auto-kicking as  a feature.  On  a marketing  or
grant-related list where head count  is everything, I would probably view
any form of renewal as undesirable.
 
  Eric