SmarterTools, please hear this one out and your feedback would be appreciated.
Administrator > User Defaults
"User defaults are applied to new domains only. To push these settings to existing domains so they can be applied to users within, use Propagation."
So I changed Mailbox Size Limit MB from 200 to 1000. Everybody deserves a gig mailbox nowadays, right? In reading the above note, I assume my change applies to new domains only. Okay, so I need to propagate the DEFAULT (not ACTUAL) mailbox size to all domains.
This action set all 15,000 mailboxes on our server to ACTUAL 1000 MB Limit!
The phone started ringing. I immediately used the propagation tool again to set all mailboxes to unlimited. Finally, 36 hours later I was able to robocopy and restored all settings.json files for our users from a backup. Restarted SmarterMail. All was good again.
I find the verbiage a bit misleading. Otherwise, the propagation action may not be correct. Maybe I'm just confused. As always, thanks for listening.