Cancel dropship sales order lines for orders that are over 90% fulfilled, without triggering email

We have a requirement to cancel existing dropship sales order lines that have been fulfilled beyond 90%, while ensuring that no email notifications are sent to the supplier.
Since this is a recurring activity, we explored the use of the undershipment tolerance feature to automatically close dropship sales orders once fulfillment exceeds 90%. However, this feature is not functioning as expected—it does not close the sales order line.
Could you please advise on how this requirement can be achieved?