IMPORTANT NOTE: SmarterMail data should be migrated to a new server that's running the same build number. Do not follow these steps to migrate a SmarterMail 16.x or prior installation to a new server running the current 100.0.xxxx build. If you wish to upgrade along with your domain migration, you must migrate to the server then perform the upgrade, or perform the upgrade on the old server then migrate.

Follow these steps to move a SmarterMail domain to another server:

Before beginning, make a backup copy of the domains.json file (default install path is C:\Program Files (x86)\SmarterTools\SmarterMail\Service\Settings\) and the domain folder (default install path is C:SmarterMail\Domains\[domain_name]).
Stop the SmarterMail service on both servers.
Move the domain folder from the old server to the new server. The default install path of the domain folder is C:SmarterMail\Domains\[domain_name]).
Edit the domains.json file with Notepad on the old server. The default install path is C:\Program Files (x86)\SmarterTools\SmarterMail\Service\Settings\.
Locate the entry for the domain. It will be displayed in the following format:

    "domain.com": {
    "data_path": "c:\\SmarterMail\\Domains\\domain.com"
    },

Copy the domain entry from the file and keep it on hand. Then delete the domain entry and save the file.
Make a backup of the domains.json file on the new server.
Edit the domains.json with Notepad on the new server.
Paste the domain entry that was cut from the file on the old server, making sure to adhere to the proper naming/formatting of the name.
Save the file.
Start the SmarterMail service on both servers.
Modify the primary MX record to the new IP. This can take up to 24-48 hours for propagation.