My wife is travelling in the US and has her Australian iPhone (which is roaming) and a iPhone with a US SIM.
I can iMessage her OK. I can also iMessage my daughter (in Australia).
When I try to send a message to both my daughter and wife it suddenly goes as SMS (for which I have to pay roaming charges).
Up until last night it was working OK.
How can I force my iMac to use iMessage NOT SMS?
Best Answer
Couple of things to try:
Note with the second point there. There used to be an issue whereby Messages on macOS would group the chats separately if you've sent messages to different addresses of the same contact. Not sure if this has been resolved, but it was frustrating.