Resolve pending migrations in cases where a mailbox for an user account exists both in Exchange On Premises and in Exchange Online.
Removes the on premises mailboxes if the number of items in the mailbox is below a specific threshold (initialized with 300) and creates a remote mailbox.
The email addresses are preserved and the remote routing address is taken from the Exchange Organization Configuration (using Get-OrganizationConfig).
Populate a .csv file with a list of mailboxes or pass the argument -user followed by the identifier of the mailbox for an ad-hoc run on a single user.