The Canadian firm said in a statement that "service issues" had affected BlackBerry customers in Europe, the Middle East and Africa.
Embarrassingly, the outage came on the day that Apple announced its new iPhone 5.
"Our apologies to any customers impacted by the BlackBerry service issue today. We can confirm that services have been restored and are now operating normally," said RIM.
BlackBerry UK managing director Rob Orr later reiterated that the problems had been resolved.
"Some users experienced issues with BlackBerry services today. Apologies for any inconvenience caused. All services now operating normally," he tweeted.
The outage came almost a year after millions of BlackBerry customers endured three days without their email, internet and BlackBerry Messenger services due to a "core switch failure".
RIM's shares slumped to a nine-year low in June after Morgan Stanley downgraded the stock of the once mighty smartphone maker.
The company has already announced plans to cut 5,000 jobs and launched a shakeup of its management team to turn around its fortunes.
But BlackBerry 10, its new operating system, has been delayed to next year, meaning RIM wil miss the Christmas market and risk losing even more ground to the iPhone and handsets running Google Android or Microsoft's Windows Phone.