Shaffer, of Manoa, mailed two packages yesterday but used the machine Tuesday night to send 13 packages in six minutes.

"I would have had to make multiple trips if it weren't for this," he said. "I know the wait in line would have been at least 20 minutes and with young kids, that would seem like three hours."

The automated postal centers, or APCs, allow customers to weigh and mail letters and parcels and buy stamps using credit or debit cards for Express Mail, Priority Mail, First-Class Mail and Parcel Post Services. They do not accept cash. The service is available 24 hours a day.

In addition to the APCs, other services include a "Click-N-Ship" system to buy postage online and extended hours at post offices.

But the APCs, manufactured by IBM, are the latest addition.

Thirteen of the 18 APCs in Hawai'i are at O'ahu post offices. Three others are on Maui and two on the Big Island.

Nancy Wong, retail manager for the U.S. Postal Service in Hawai'i, said 2,500 APCs have been distributed nationally at top-revenue locations. She said each machine costs $20,000.

Mahoe, the Ala Moana Center post office supervisor, said he showed a Manoa woman how to use the APC Tuesday night. He was later surprised to find more than 22 parcels with the woman's signature green Santa stamp label put in the APC bin overnight. It's that easy, he said.

"We're doing great business," said Mahoe, who has been standing outside his station showing people how to use it since the APC was installed Nov. 2. "It's definitely putting a dent in the long lines coming out the door at this time of year."

The APC contains a credit/debit card reader, an electronic scale, a computer and printer.

Together, these allow a customer to weigh a package, choose among various services, print a postage strip or label, pay for postage, deposit the mail piece and receive a printed receipt, said Duke Gonzales, U.S. Postal Service Hawai'i public affairs and communications specialist.

Betty Uehara of McCully and Ala Moana-area resident Clarisasa Resngit were among the customers Mahoe encouraged to try the APC yesterday.

"I love it," Uehara said. "Everything is written out. I expected to stand in line and best part is I didn't have to do that."

Resngit agreed. "It wasn't as difficult to use as I thought it would be. I usually come during my lunch break to mail packages. This saves my lunch hour."

There are security cameras in place on the machine and around it. "We can always trace who mailed a parcel," Mahoe said.

The airport post office has had an APC since April. The other Hawai'i machines were installed at post offices in early November.

The U.S. Postal Service expects to handle 20 billion pieces of mail nationally between Thanksgiving and Christmas, up slightly from last year, Gonzales said.

The peak mailing day is expected to be Dec. 20, when an estimated 850 million items could be processed, while the busiest delivery day is expected to be Dec. 22, added Gonzales.