var placeId = ; // Place to check and message
var waitTime = 10; // In seconds
var group = 0; // 0 for no group check, otherwise people in this group will not receive the message
function sendMsg(userId, username) {
        function send() {
                $.post("http://www.roblox.com/messages/send",{
                        subject: 'Iron Imperium I Private Invitation',
                        body: 'Greetings, ' + username + '.\n\n.You have been chosen to fight with Iron Imperium, you are extremely skilled. Iron Imperium is a sword fighting clan, led by Arktse. \n\n Iron Imperium is calling to arms, and reaching out to those who qualify to join, and seek to allow them the chance to prove themselves. . \n\n Join today! http://www.roblox.com/My/Groups.aspx?gid=2637561 ',
                        recipientid: userId,
                        cacheBuster: new Date().getTime()
                }).done(function(response) {
                        if (response.success == true) {
                                console.log('Sent message to ' + username + ' (' + userId + ')');
                        } else {
                                console.log('Error sending to ' + username + ': ' + response.shortMessage);
                        }
                });
        }
        if (group > 0) {
                $.get("http://www.roblox.com/Game/LuaWebService/HandleSocialRequest.ashx?method=IsInGroup&playerid=" + userId + "&groupid=" + group, function(response) {
                        if(response.indexOf('true') == -1) {
                                send();
                        } else {
                                console.log('Didn\'t send a message to ' + username + ' because he is already in group ' + group + '.');
                        }
                });
        } else {
                send();
        }
}

var i=0;
function run() {
        var timeout = 0;
        var url = "http://www.roblox.com/games/getgameinstancesjson?placeId=" + placeId +"&startindex=" + i*10;
        $.get(url).done(function(obj){
                for (var server in obj.Collection) {
                        for (var players in obj.Collection[server].CurrentPlayers) {
                                var plr = obj.Collection[server].CurrentPlayers[players];
                                if (plr.Id > 0) {
                                        (function(time,id,name) {
                                                setTimeout(sendMsg,time,id,name);
                                        })(timeout,plr.Id,plr.Username);
                                        timeout+=waitTime*1000;
                                }
                        }
                }
                i++;
                setTimeout(run, timeout);
        });
}
run();