For the past week or so I am not able to send iMessages to anyone who does not have an iOS device. The recipient's name is in red and the message will eventually be undeliverable. This happens on my iPad Air2 and MacBook Pro. But, my iPhone 6 will work. All devices are running the latest and greatest(?) software. MacBook Pro is a mid-2012. Any solutions? I've tried resetting the network settings on the iPad, but no change. Thanks!