The chat in Stalgath is very simple, you start out in local chat everytime you join the server. This chat is IC and has a distance of 48 blocks. If you type /global (message) it will send 1 global message and then revert back to local. If you type /global then press enter you will switch to global chat and every message you type will be in global until you switch back to local. Global is OOC and throughout the worlds. Messages are OOC and between two players, for example I, Damnatum want to send a message to Fettsex. I would type /msg fettsex hey how's it going? Then Fett would see a message from me saying "Hey, how's it going?" this message and all others like it are OOC. Finally there is an IC messaging system that is long distance. To use realmail you need to set up a mailbox, to do that type /rm setmailbox and be looking at a chest. This chest will become your mailbox, all mail that is sent to you will be sent to this chest and you will receive a notification saying "You've got mail!" to send mail you need to get a book and write a message, sign it and then type /rm send (playername) which will send the book to that player's mailbox.
Global: OOC
Local:IC
Private:OOC
Mail:IC