Puts every person's department history the import changed back exactly as it was before it. Directory people the import added leave the directory again, with the email links it wrote for them; an email link that existed before the import and that the import resolved to one of them goes back to unresolved. Refused with 409 while a later import changed the same people (undo that one first), or when their departments changed after the import in any other way, or when a department it would restore has been deleted since, or when the email links of people it added changed since. Records the undo in the import history and the audit trail.