@Override
    public void start() throws IllegalStateException {
        super.start();
        deliverHandler = new SocketPacketWriteHandler(XMPPServer.getInstance().getRoutingTable());
    }
The handler that does the actual delivery (could be a channel instead)
xmppserver/src/main/java/org/jivesoftware/openfire/spi/PacketDelivererImpl.java