This can somehow reset the app to fix iMessage not delivered on Mac. Sometimes re-enabling iMessage on your Mac is helpful to solve issues specific to iMessage.
You can browse a webpage to test the connection. Thus, make sure your Mac is connected to the Internet that can work properly. IMessage requires an Internet connection to work and it can be a personal hotspot, Wi-Fi, or Ethernet.
MESSAGES FOR MAC NOT SENDING HOW TO
How to Fix iMessage Not Working on Mac Ensure Your Mac Has an Internet Connection
To learn more, go to How to Fix: Android Not Receiving Texts (7 Simple Methods). Tip: If you are using Android, sometimes you may find it can’t receive texts.