Something like this?
Javascript code:
var oEmails = [
'email1@hotmail.com',
'email2@hotmail.com'
];
function OnEvent_ChatWndReceiveMessage (pChatWnd, sOrigin, sMessage, nMessageKind) {
for (var oEmail in oEmails) {
if (pChatWnd.Contacts.GetContact(oEmail) && pChatWnd.Contacts.Count === 1) {
return '';
}
}
}