Research in Motion Ltd. said in a message to corporate customers that a "critical severity outage" left users with no ability to send or receive e-mail messages.
E-mail service stopped before 1 p.m. Pacific time and began to return about four hours later.
The blackout upset some business owners who rely on the devices.
"We're just shut down," said Jesse Fowler, president of Tellus Group, an environmentally oriented Santa Ana construction firm.
"We could have missed a lead or something that we should have responded to immediately," he said. "For a business like mine that does business out of state, it can make or break contracts."
In Barcelona, Spain, at a worldwide wireless conference, Arthur Goikhman found he couldn't send messages home to New York and that others were having the same problem.
"It wasn't pandemonium here," said Goikhman, the chief executive of mobile game maker Cellufun Inc. "No one took out their phone and started stomping on it, but it was quickly the chat of the room."
Though the outage didn't make him angry, he said, it did make him realize that "we're completely accustomed to instant communication, and when it doesn't happen, we get shaken up."
Executives at Research in Motion, based in Waterloo, Ontario, were not available for comment.
They also were unavailable for several days last April when a massive outage gave BlackBerry owners some perhaps unwanted relief from thumbing the tiny keyboards on the devices, which have become so addictive they've been dubbed CrackBerrys.
At that time, executives were roundly criticized for failing to keep their customers informed about any progress during the 14-hour outage.
After several days, the company acknowledged that an upgrade had gone awry and had triggered a series of glitches that led to the outage.
Monday's notices indicated that the executives had learned their lesson, though they failed to supply any information to the public on company websites.
The e-mail blackout didn't affect phone service or instant text messaging, though it did block Web access for many.
Not all carriers or customers were affected.
At least some customers of Rogers Communications Inc., the biggest Canadian carrier of BlackBerry service, had no problems.
"I expect some IT [information technology] managers will be following this situation and looking to diversify their corporate strategy," said analyst Michelle Warren at the Toronto office of Info-Tech Research Group.
"If the pain continues for a long period of time, you will see some of them look for an alternative service like Windows Mobile, probably as an addition to BlackBerry service," she said.
The outage occurred as Research in Motion has been enjoying rapid growth as the favored device for much of corporate America and the federal government, fending off threats from such players as Apple Inc.'s iPhone and a series of Nokia smartphones.
Analysts expect the company to have nearly 14.2 million customers by the end of the month, a 73% increase over 8.2 million a year earlier.