A system failure knocked out BlackBerry service for millions of customers yesterday and today, but the company announced late this morning that service for “most customers” was restored, CNNMoney.com reported.

A statement from the company said: “A service interruption occurred Tuesday night that affected BlackBerry in North America. E-mail delivery was delayed or intermittent during the service interruption.”

“Root cause is currently under review, but service for most customers was restored overnight and RIM is closely monitoring systems in order to maintain normal service levels,” the statement said.

Some users had reported intermittent service, others have gotten bundles of backed-up e-mails, and still others have no access at all. Even with the system back, some users may experience delays as the company processes the backlog.

The stock of Research in Motion Ltd., which sells the BlackBerry device and service, sank about 1 percent in early trading on the Nasdaq Stock Market.