Hi, For a while I have had this iMessage weird bug. You should see the attached files for illustration, here is what happens. It happens regularly but with no apparent reason: it will work for days or weeks, then some day the bug will start. It can happen with any contact, but it doesn't happen to all the contacts at the same time. I first send an imessage. The phone quickly says it was "not delivered" with an "!". Clicking then ! and try again doesn't do anything (stays as not delivered". If instead I choose "send as text message", it will properly send as text message. After doing that I can send imessage again to the contact, until the next time the bug comes. Some more details: To me it looks like it started when they introduced the imessages and text messages forwarding to macOS. Also, turning off and on imessages seams to solve the problem for a while, but choosing to send as text message is a quicker fix. Any ideas?