As the designated provider of the universal service obligation (USO) in the Netherlands, our job is to maintain country-wide mail coverage and deliver on specific quality targets, which do not apply to other postal companies. In 2020, we saw the anticipated benefits and synergies resulting from the integration of Sandd surpass our expectations and occur ahead of schedule. We have long argued that the consolidation of postal networks is vital to safeguard accessible, reliable and affordable postal services in the Netherlands, and the consolidation of Sandd will help cushion the decline of the postal market in a socially responsible way.
The Covid-19 pandemic accelerated volume decline in bulk mail volumes and provided a boost in greeting cards and mailbox gifts, as people reconnected with the value of physical mail. In a declining market, one of our key challenges is securing accessible and reliable postal services at affordable prices. We continue to implement cost savings initiatives, such as adjustments to the sorting and delivery process, streamlining of staff and centralising of locations. We are also innovating our services and solutions, while intensifying dialogue with customers so that we can meet their future needs, working to ensure that mail remains an attractive option alongside the digital solutions that our customers have at their disposal.
From the beginning of the Covid-19 pandemic, we saw a sharp rise in greeting cards and letterbox parcel volumes, as people reconnected and sent cards and gifts to friends and family via mail. In December, we delivered 50 million Christmas cards, 10 million more than expected. At the same time, bulk mail volumes declined significantly, with many direct mail campaigns postponed or cancelled. The additional volume decline was partially offset by a positive price mix effect.
We successfully integrated Sandd into our mail network in 2020. The consolidation of both postal networks was vital to safeguard accessible, reliable and affordable postal services in the Netherlands. And to provide thousands of employees with greater job security, while ensuring that we retain our moderate pricing policy.
Key success factors included using a dedicated team from Sandd and PostNL to design the new mail organisation, investing heavily in the onboarding of new colleagues through intensive communication and open house events, and ensuring colleagues from Sandd were given a warm welcome at their new location. We also focused on our customers, matching new processes to their expectations and providing tailored solutions when required. Customer and employee surveys showed a high level of satisfaction with both the integration process and outcome.
We realised larger-than-expected synergies ahead of time through the Sandd integration. We have seen substantial synergies from combining the networks into one network, operational synergies from combining central functions and optimising the sorting processes, and greater cost efficiency. We have also seen more satisfied customers. Gross synergies amounted to €79 million for the whole year.