Netflix, the DVD rental service, is suffering from the biggest shipping problem in its history, delaying delivery of those familiar red-and-white envelopes to millions of its customers.

The Los Gatos, Calif.-based company Thursday told its 8.5 million subscribers that it had been experiencing “severe technical issues” that had prevented it from mailing movies and TV shows.

The problems began Monday night and halted all shipments Tuesday.

On Wednesday, the company was able to send about half the discs subscribers had ordered from its 55 U.S. distribution centers.

The problem, which Netflix spokesman Steve Swasey wouldn’t identify, has prevented delivery to about one-third of the company’s members, or about 2.8 million subscribers, who have sent discs back and are awaiting their next shipments, he said.

In a message on its home page, Netflix said, “We apologize, and we’ll be automatically issuing credits to all of you whose shipments have been delayed.”

Netflix, which ships about

2 million discs a day, has missed shipments only one other time since it launched in September 1999. That delay occurred in March.

Netflix then issued a 5 percent credit in monthly fees to members whose discs were delayed by one day and a

10 percent credit for shipments that were delayed for two or more days.