Hi James_the_series_3_owner,
Thank you for posting to Apple Support Communities.
With the messages not going through to the contact you're attempting to send to, it seems like there is a disconnection at some point. Can you test this on another network?
We also have some steps to help recover if you can't send or receive Messages on your Mac. Follow the guidance below:
• Restart your Mac. Choose Apple menu > Restart, then click Restart.
• Make sure that your software is up to date. Learn how to update the software on your Mac.
• Make sure that your Mac is connected to the Internet. To check your Internet connection, try loading a page in Safari or another web browser.
• Check that the date and time is set correctly on your Mac.
•Make sure that you enter the correct phone number or email address for the contact.
This information is provided in If you can’t send or receive messages on your Mac - Apple Support
Take care.