Use a chat room
Using chat rooms is similar to participating in a group conversation, but you don’t need an invitation to join a chat room.
All users of a chat room must use a Jabber account. iMessage doesn’t support chat rooms, but you can have a have a group conversation with iMessage.
Create or join a chat room
Choose File > Go to Chat Room.
Click the Account pop-up menu and choose the messaging account you want to use, then do one of the following:
Create or join a chat room: Enter the name of the chat room in the Room Name field, then click Go.
Save a chat room: Enter the name of the chat room in the Room Name field, then click the Add button
. To enter the chat room, click Go.
While you’re in the chat room, you can invite more people. Click the Add button , choose someone, enter an invitation message, then click Invite.
Limit message history displayed when you join a chat room
You can choose how many messages of the previous conversation to show when you join a chat room. You can use this setting to see the conversations that occurred before you joined the chat room.
Choose Messages > Preferences.
Click Accounts, then select a Jabber account.
Click Chat Settings.
Select “In chat rooms, show,” then choose an option from the pop-up menu.