Anthea,
 
The answer  is very simple.  There is no rule  on the Internet,  beyond a
very small number of technical rules  which are enforced only through the
fact that,  if you don't  respect them, your  computers won't be  able to
talk to other people's computer. So you have to send network packets in a
particular format  and in a  particular order,  but beyond that  there is
absolutely no control and you can do  whatever you please - pull the plug
without telling anyone,  drop people's subscriptions, change  them to the
new addresses, whatever.
 
  Eric