The following appears logged when trying to migrate a site mailbox:
15:02:52 ERROR: [8803-94-9-8100275E]Unable to open server 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXX@DomainName.onmicrosoft.com'
15:02:52 Check that mailbox address, user name and password are valid.:
15:02:52 Error 8100275E License or Service Tag
WORKAROUND:
