In Progress migrations show failed state with error:
“Error: ExternallySuspendedException: Email migration failed for this user because the subscription was suspended externally to the Migration Service”
When a license expires in Mailbox Shuttle or the allowed licensed user limit has been exceeded, Mailbox Shuttle issues a suspend command to the In Progress migration batches. The migrations will then be put in a suspended state in Office 365. There is a known issue in Mailbox Shuttle 1.5 where the migrations are not resumed correctly after a new license is applied to the system.
Restart the Mailbox Shuttle Office 365 Import Service.