A part-time postman from Devon hoarded more than 30,000 letters and packets after not having enough time to deliver them, a court has heard.
Paul Willicott, 44, from Fernicombe Road, Paignton, kept the mail in his house, car, shed and a rented garage.
Torbay Magistrates' Court heard he had complained to his employer, Royal Mail, which has now introduced a new system.
He admitted two charges of delaying the mail. He was bailed and told he faced a community-based penalty.
In June, a member of the public spotted him putting mail in the garage, prosecutor, Stephen Nunn said.
Post Office officials investigated and found 174 undelivered packets.
In the boot of his car, they found six bags containing 798 postal packets, and 67 bags with 30,130 items of mail in his house, the court heard.
Defence lawyer, Richard Porritt, described it as a "quite unusual case".
Willicott worked a four-hour shift but it took him five or more hours to complete the round, he added.
Mr Porritt said the situation snowballed out of control.
Willicott admitted two charges under the Postal Services Act of being an operator who delayed a postal packet or mailbag between October 2008 and June 2011.
Mr Nunn said Willicott was employed as a postman working from the Torquay delivery office from 2008 until June 2011, when he was sacked.
A number of vans were used to collect the mail and redirect it, costing Royal Mail £3,400, Mr Nunn added.
Willicott was bailed and told that he faced a community-based penalty.
He will be sentenced next month.