A shipment can be retained in customs because more information is needed, if this is the reason for the customs authorities to be contacted. It is also possible that the shipment will be associated with certain taxes. Customs clearance processing times depend on each country 

Occasionally, if the driver is in the area and does not locate the address you can contact to confirm the delivery address. However, it is not common practice. However, if you have entered your email in your order you will receive a DHL notice with the expected delivery date. 

It depends on the type of product you purchased, of its value, from how the seller has documented the purchase and the home country. If customs imposes a tax or duty on the merchandise, DHL will pay you on your behalf, but you will then need to pay it even if you do not accept the delivery of the goods. Before making your purchase, please check the terms of purchase with your shipper.

You can see the General Terms and Conditions for Carriage of DHL eCommerce Spain by clicking here