Firstly, you will likely need to be familiar with the game World of Warcraft to do this.
What i need done is:
-A program (can be external to the game, or an ingame addon) that gets the name of all people online at a current time, and compiles them onto a list.
-Later this program automatically and instantaneously ingame mails or ingame whispers the people on this compiled list of names with a predefined message that i have written, so that i can advertise ingame.
This is basically it. For further discussion, please contact me and we can discuss it further.