The 42-year-old man, who has not been named, was arrested after police discovered a stash of thousands of letters stolen over a period of ten years.
The ex-postman has been charged with violation of trust as a custodian of private documents and breach of confidentiality for his stealing spree, which began in 2004 and lasted until 2014.
Spanish police launched an investigation when they learned that a man had accumulated thousands of letters in his house in Alcoy, near Alicante.
They discovered that the owner was a former employee of the Spanish postal service, who worked for the local post office in the town of Ontinyent, Valencia.
"Robbed more than 3,200 letters over 10 years when he was working for postal service and kept them in his box room in Alcoy," tweeted Spain's National Police.
Police found 3,200 letters in the postman's possession, which included over 1,000 from the regional Valencian government, 162 missed delivery notes, driving licenses, court notices, energy bills, bank letters, personal letters and magazines.
After examining the correspondence, police saw that the ex-postman had been stealing letters during a ten year period, from 2004 until 2014.
He was fired in 2014 when the post office noticed "irregularities" in his delivery methods, according to a statement issued by Spain's National Police.
The postman worked an area along Spain's popular Costa Blanca which included the towns of Ibi, Alcoy, Muro de Alcoy, Cocentaina and Ontinyent, as well as the city of Alicante.