Assignment Notification emails

Hi,

   I am using the Bulk API to create call records and related Contact records (if appropriate). One of the filed that is getting populated is "assigned_user_id".

When records are created Assignment Notification emails are sent to the User the call has been assigned to. Is there a way of creating these Call records using the API without triggering a Assignment Notification email? or is the only option to turn off Assignment Notification emails at the system level or User level using the Administration options?

Regards - Martin