- Independent Authority for Public Revenue (IAPR)
- Hellenic Authority for Communication Security and Privacy (ADAE)
- Hellenic Data Protection Authority (HDPA)
- General Directorate of Consumer Protection of the Ministry of Development
- European Commission's platform for online dispute resolution (ODR)
- Hellenic Consumers’ Ombudsman
- The Greek Ombudsman
- Ministry of Finance
- European Committee for Postal Regulation (CERP)
- European Regulators Group for Postal Services (ERGP)
- Universal Postal Union (UPU)