That's because their mail carrier stashed it in a storage locker---ala Newman from "Seinfeld".
Postal carrier Jill Hull, 34, pleaded guilty to storing nearly 10,000 pieces of mail---including 988 pieces of first class mail and 236 parcels --- in a locker she had rented in 2006, the Daily News reported today.
"I was unable to deliver all of the mail," Hull said, according to the News. "Instead of asking for help ... I took it upon myself to place the mail in a storage facility."
Her boss said, "We just didn't understand it. It's such a stupid thing to do. ... It's like it got dark and she didn't know what to do with the mail."
Michigan's mischievous mail carrier isn't the first postal employee to shirk on her work.
According to the U.S. Postal Service there were 333 "Newman" cases, in which mail was stolen, delayed or destroyed by employees or contractors, in 2008. Hull faces up to a year in jail and $100,000 in fines.