ODM Mailbox migration Reset option (4371984)

ODM introduced a new option for Mail Migration. 'Reset Migration'

What exactly is the ODM mailbox migration Reset option for? 

Does ODM delete the target mailbox data when it's enabled?

Once a successful migration has taken place, a changeSetID is recorded. This is queried on the next migration to perform an incremental.

• The 'reset migration' option instructs the migration engine to ignore this, and query all items.
• This does not cause duplication.
• Select this option only when you need to do a full re-migration and not a delta sync of your source content to a target.
• For example,you want to delete content from the target mailbox and want to re-migrate the source again.

Alternatively, removal can be done outside of ODM toolset, using PowerShell or other 3rd party tools.