TORONTO, Feb 12 (Reuters) - A major outage hit BlackBerry users in North America on Monday, cutting off wireless e-mail for everyone from busy executives to political campaign staff on the eve of three U.S. presidential primaries.

The problem, which BlackBerry owner Research In Motion described as a "critical severity outage" affecting users in the Americas, once again raised concerns about the stability of the e-mail service 10 months after a widespread crash last April.

RIM said in a later statement that data services in the Americas experienced delays on late Monday afternoon, around 3.30pm Eastern time, but were restored in the early evening at around 6.30pm.

But by about 7:00 p.m. Eastern time some users said a few e-mails were trickling through while others continued to be without service.

Carmi Levy, senior vice-president of strategic consulting at AR Communications, said reliability is a serious concern for companies like RIM because if problems become routine, they can drive customers away.

"It's a big issue and it's a growing issue," Levy said, adding that huge outages could prove to be "a major Achilles' heel" for RIM.

RIM's U.S. shares fell as much as 1.3 percent on the news, after closing up 5.3 percent in regular Nasdaq trade. On the Toronto Stock Exchange, the shares finished the day C$4.73 higher at C$94.62.

RIM notified its clients of the outage in an e-mail, but officials at the Waterloo, Ontario-based company were not immediately available for comment.

"This is an emergency notification regarding the current BlackBerry Infrastructure outage," RIM support account manager Bryan Simpson said in an e-mail sent to large clients.

The last big outage in April 2007 provoked an angry backlash from more compulsive users, who have dubbed the device "CrackBerry" due to its drug-like addictiveness. At the time, co-Chief Executive Jim Balsillie said such incidents were "very rare" and RIM was taking steps to prevent it from happening again.

RIM's worldwide subscriber base reached about 12 million people by late last year, mainly executives, politicians, lawyers and other professionals who rely on the BlackBerry to send secure e-mails. Sleeker new models are also catching on with students and others outside professional circles.

Jen Psaki, a spokeswoman for Democratic presidential hopeful Barack Obama, said, "While the outage did confirm our widespread addiction to BlackBerry service, fortunately it did not cause more than a temporary inconvenience."

Voters go to the polls on Tuesday in Virginia, Maryland and the District of Columbia, the latest battleground in a tight race between Obama and Hillary Clinton for the Democratic nomination in November's election.

U.S. mobile phone service provider Verizon Wireless said the outage was affecting all carriers' BlackBerry e-mail service in North America. It said Verizon Wireless customers can still make calls on their BlackBerry.

Some appeared to enjoy a respite from the device.

"It made my life a little bit easier, since I didn't have to reply," Liberal Party spokesman Jean-Francois Del Torchio said from Parliament Hill in Ottawa.

"But when I arrived at my desktop and I saw all the e-mails I received, I was like, 'Oh, I still need to work'," Del Torchio told Reuters.

(Additional reporting by Yinka Adegoke in New York, Scott Hillis in San Francisco, Jeff Mason in Baltimore and Randall Palmer on Ottawa; Editing by Braden Reddall/ Elaine Hardcastle) ($1=$1 Canadian)

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