After a lot of trial an error I am going to leave this out there in case someone else runs into. I use the default location. If you do not have a backup of your files, make a copy of this file first.
Open the file, I use Notepad++, C:\Program Files (x86)\SmarterTools\SmarterMail\Service\Settings\domains.json
My data is on the D drive
Check for your domain, the format looks similar to this, I have masked my domain:
I went to the end make sure you have a comma (,) on all except the last one. I missed the one before where I copied and pasted.
Restart SmarterMail service
Restart the Website, or the web server
So far I can send and receive from one of the users, they may have lost a few days of emails, but luckily it was over the weekend.