Some 20,000 pieces of mail - many more than a decade old - have been recovered from a postman's garage in the US city of Philadelphia.
Tubs of undelivered letters were discovered in April when the US Postal Service worker missed several days of work and managers visited his home.
The FBI said it took more than three postal vans to remove the mail, some of which dated back to 1997.
Investigators are still trying to find the postman so they can question him.
Delaying mail and stealing mail are both federal offences in the US.
The missing mail is said to have included large numbers of cheques, bills and official letters. Many have since been delivered to bewildered residents of Bustleton, a north-eastern suburb of Philadelphia.
"I got mail today from 2007," Kevin Carpenter told ABC News. "Pay-cheques, things like that that I needed - stuff from the social security administration and the IRS."
"I asked Dave [the postman] and Dave said he hadn't seen it but as soon as he got it he'd call me," Mr Carpenter added.