How to migrate Shared Mailboxes with On Demand Migration (ODM).
解决办法
Create and run a Discover task
If the Shared Mailbox exists in the target already, create and run a Match task. Otherwise if ODM is creating the target shared mailbox, create and run a Migrate Accounts task
Create and run a Mail migration task. You will be prompt to choose a license option however if the shared mailbox does not have a license on the source and target no license will be applied.