Hi Henry,
Are these the steps you followed when migrating the server?
Migrate SmarterMail to a Different Server:
You'll need to copy over both the Domains and Service folders:
C:\SmarterMail\Domains
C:\Program Files (x86)\SmarterTools\SmarterMail\Service. (Note that mailConfig.xml and domainList.xml are the only files absolutely required from this folder.)