DPD offer a service called 'predict & follow my parcel', this is a service that allows your customers (the shipment recipients) to track their parcels on a real-time map all the way down until the final 15 minutes of the time-slot. A one hour delivery window is also provided so that your customers don't have to wait in all day.
DPD 'predict & follow my parcel' service also offers alternatives for your customers if they they are not in when the parcel is delivered. They can select either to have the parcel dropped off at a near by DPD collection point, left in a safe space, left with a neighbour or reschedule the delivery for another day. This can all be done by the customer on their phone while their parcel is out for delivery. This of course does then mean that your customers will need to include their mobile phone number when making the order from your online store.
For additional information on or help with DPD's 'predict & follow my parcel' service you can either check either DPD's own guide or contact our support desk.