to leave a message for a group of users you usually use a public distribution list. Create a public DL with all the folks you want to get messages and then assign that distribution list as the message recipient on a call handler - setup the call handler with an appropriate greeting or whatever you want and then set it up to take a message after playing the greeting. All members of the distribution list will get a copy of the messages left for that call handler.
The distribution list can also be addressed by subscribers in the message addressing conversation, of course...
