Some secure online portal would be nice for the GP or municipality.
The delivery issues can be solved by introducing a standardized address system for Spain but that would take decades to roll out. Some people I know don’t even have an address, they just use the land registry number. Or just the name of their village + surnames, which is typically good enough for the standard mail (but not good enough for DHL/UPS/DPD packages, their drivers want your location via WhatsApp)
The delivery issues can be solved by introducing a standardized address system for Spain but that would take decades to roll out. Some people I know don’t even have an address, they just use the land registry number. Or just the name of their village + surnames, which is typically good enough for the standard mail (but not good enough for DHL/UPS/DPD packages, their drivers want your location via WhatsApp)