If you do not want vendors to be automatically notified when order reaches a specific status, you can setup that notifications will be sent out only when you manually switch the order to be a status, which is outside of normal Magento workflow.

An example of a standalone solution:

1. Create app/etc/modules/udropship-custom.xml:

udropship-custom.xml

<?xml version="1.0"?>
<config>
    <global>
        <sales>
            <order>
                <statuses>
                    <udropship translate="label"><label>Sent to Warehouse</label></udropship>
                </statuses>
 
                <states>
                    <new><statuses><udropship/></statuses></new>
                    <pending><statuses><udropship/></statuses></pending>
                    <processing><statuses><udropship/></statuses></processing>
                    <complete><statuses><udropship/></statuses></complete>
                    <closed><statuses><udropship/></statuses></closed>
                </states>
            </order>
        </sales>
    </global>
</config>

2. Open System > Configuration > Drop Shipping > Vendor Options 3. Update Make Available to Dropship on Order Status(es) and select Notify Dropshippers 4. Save configuration.

Now, the orders will be available to dropshippers and notifications will be sent only when store owner will manually set order status to “Notify Dropshippers”