Shopping online has many advantages. You can put on your pj's, open a bottle of wine and avoid the crowds—all while crossing items off your list.
But what happens when that convenient process is ruined by late delivery of a package, with the result being no gift under the tree?
(Read more: UPS, FedEx struggle with delayed Christmas gifts)
For the first time, StellaService, which rates retailers on customer service, scored store websites on meeting promised delivery dates for holiday orders.
On the advertised cutoff dates for standard orders to be delivered by Christmas, mystery shoppers bought one product from a group of 25 retailers (including Wal-Mart Stores, L Brands' Victoria's Secret and Amazon), sending the gifts to three locations around the United States.
Eight of the companies failed to get their products to recipients by Christmas in at least one region. Of 75 packages, nine packages—or 12 percent—missed the promised delivery. Eight of those nine late deliveries were shipped via UPS, StellaService said.
"I think that what we're seeing this year are some growing pains in e-commerce," said Ty McMahan, director of content at StellaService. "More people shopped online this year, so this is kind of the first year we're stress testing the infrastructure."