Good morning, I hope this comment finds you well. I'm sorry to hear you're having trouble with this! The failed to load domain error might indicate one of a few possibilities:

- Domain folder cannot be accessed by SmarterMail due to permissions issues. Does the domain load appropriately when stored locally on the server? If so, please verify the permissions on the problematic drive as this would indicate the SmarterMail service can't load those files. 

- Domain is missing critical pieces of its structure due to failed copy operation. Can you confirm the domain folder is the same before/after move? 

- JSON configuration files within the domain folder may be corrupted or missing. Do you see any blank files or strange corruption characters contained in the domain's JSON files? 

Some things you can take a look at to determine the root cause are in revewing the convert-status page which should reference any errors relating to this domain. The convert-status page is present under our latest release, and can be accessed like so:

http://localhost:9998/interface/convert-status
or
http://mail.your-domain.com/interface/convert-status

Once there you'll need to log on with a system administrator account to review the domain list and any errors being reported.

Additionally, you can check the Error logs in SmarterMail (from a system administrator account) to see what logs are present relating to this domain name as well. Lastly, you can use a service like jsonlint.com to validate the JSON files contained within the domain and user accounts to confirm whether or not corruption is present. 

Finally, I recommend submitting a support ticket with us on this if you have active Maintenance and Support, as we'd be happy to investigate further and determine the root cause for you.