About a year ago, a single package appeared on Karen Holton’s porch in San Jose, Calif. She was bewildered; she had not ordered anything, and neither had her neighbors. So she dropped the package at U.P.S., and thought that was the end of it.

She was wrong.

“They kept coming,” Ms. Holton, 55, said in an interview on Friday.

It was just the beginning of a yearlong ordeal as the unintended recipient of misdirected Amazon returns.

Over months, an onslaught of cartons and boxes grew at the doorstep of Ms. Holton’s home, a single-family house on a corner lot, in stacks so high that she was unable to easily use her door or get to her mail.

“They were always put on my porch, or if the porch was too full, they would pile up outside,” she said. “It was hit and miss. A couple of weeks there were none. And then 10 in a week. No rhyme or reason to it.”

“I had to move them if I wanted to be able to use my porch or get into my house,” she said.

Eventually, she started to move them to the carport, and covered the boxes with a tarp, worried about rain, fire and rodents. The chaotic stacks of mismatched packages grew into musty walls so tall that she was unable to park there.