Restrict access to all employees distribution list in Exchange Server
If you are using Exchange Server, you can restrict who has access to the
all-employees distribution list. Whatever you called it, you can prevent someone
from accidentally sending a private message to everyone on the server and you
can prevent people from responding to an all-employees distribution creating
annoying spam. On the properties dialog for the distribution list you use for
all-employees, select the Delivery Restriction tab.
Change the radio button from All to List in the Accept message from
section and add the accounts you want to have this capability. A better, easier
to manage approach is to restrict that capability to a distribution list. Create
a group you want to be able to send out all-employee broadcasts and add it to
the Accept message from section rather than individuals.