https://en.wikipedia.org/wiki/Royal_Mail which links to https://web.archive.org/web/20150224033637/http://stakeholde... (the EU directive has gone from their website and isn't in archive.org) which says
> Summary of legal position: Article 7 of the EU Postal Directive (Financing of universal services), has required the progressive – and since 1 January 2013, total - liberalisation of postal services throughout the EU.
Hopefully this qualifies as a valid citation.
“The external financing of the residual net costs of the universal service may still be necessary for some Member States. It is therefore appropriate to explicitly clarify the alternatives available in order to ensure the financing of the universal service, to the extent that this is needed and is adequately justified, while leaving Member States the choice of the financing mechanisms to be used. These alternatives include the use of public procurement procedures including, as provided for in the public procurement Directives, competitive dialogue or negotiated procedures with or without the publication of a contract notice and, whenever universal service obligations entail net costs of the universal service and represent an unfair burden on the designated universal service provider, public compensation and cost sharing between service providers and/or users in a transparent manner by means of contributions to a compensation fund. Member States may use other means of financing permitted by Community law, such as deciding, where and if necessary, that the profits accruing from other activities of the universal service provider(s) outside the scope of the universal service are to be assigned, in whole or in part, to the financing of the net costs of the universal service, as long as this is in line with the Treaty. Without prejudice to the obligation of Member States to uphold the Treaty rules on State aid, including specific notification requirements in this context, Member States may notify the Commission of the financing mechanisms used to cover any net costs of the universal service, which should be reflected in the regular reports that the Commission should present to the European Parliament and Council on the application of Directive 97/67/EC.”
IE Privatizing Royal mail was not required by the EU, instead they needed to allow for competition by UPS, FedEx etc.
They did not force the privatisation of Royal Mail; it was first made a special sort of PLC back in 2000 so that it could access private money, and arguably that helped accelerate the EU belief that postal services needed competition.
But they did force competition in EU postal delivery, and that effectively drove the decision to essentially fully privatise Royal Mail so it could compete.
It also had a very unfortunate outbreak of Crozier Disease and that didn't help.
For postal services, the same applies. EU doesn’t like the idea of a state owned or subsidised postal business, preventing the entrance of competition from companies in other member states, or allowing the subsidised entities to expand and outcompete companies in other EU states.
The EU doesn’t set national postal policy. It only requires that the basic postal service is an open to competition from entities (private and public) in any EU member. With a carve outs for the funding of universal service (I.e. making sure that every address gets post regardless of profitability), where state aid is clearly needed.