There will be a general national strike at Correos, the Spanish Post Office, taking place on several different days:
5, 15 & 22 May there will be a general strike called. Expect post offices to be closed across the country and no delivery that day.
30th April, 14 & 22nd May, there will be a “go slow”. Most post offices will be open but delivery will affected.
The strikes are against a change in working conditions.