Update, 6 p.m.:  Microsoft confirms that it has resolved the e-mail issue and that users should see their undelivered messages hit their inboxes soon. The company still has not provided details on how many users were affected, or more details on what caused the outage.

Original post: Microsoft users at businesses across the country are reporting a widespread, ongoing outage of their e-mail service that has lasted for much of  Tuesday. Some users say that they have seen their service restored this afternoon.

A Microsoft spokeswoman confirmed the outage is affecting the company's Exchange Online service but said the company is still gathering information on how many of its clients have been affected. The company recommends that users consult its service health dashboard for updates as its engineers continue to work on resolving the problem.

The company has responded to some consumers on its Twitter feed for Office 365, acknowledging the outage and saying that it is due to problems with the its Exchange Online service, which many offices use to run their e-mail, calendar and contacts services.

"Engineers are actively working on a solution to remediate impact," the company said on its help forum page.

According to Microsoft's service dashboard, all systems are running normally. But many people have taken to social networks, including Facebook and Twitter, to complain that they have been unable to send or receive e-mail for several hours.

Microsoft Outlook may not be the e-mail service of choice for many individuals, but it has long dominated the business world, and has been the product of choice for businesses looking to serve an estimated 50 million employees using cloud-based office products. Still, Microsoft has had to fend off challenges from Google and its Google Docs suite of office programs, and the pressure to compete effectively in the cloud has only increased as the market for desktop computers slides across the globe. Microsoft has reported that 58 percent of all its global revenue comes from business users, but as of 2012, analysts estimated that Google had eaten between one-third and one-half of the cloud e-mail market for businesses.

Microsoft has been focused on improving its cloud services. That's one reason many believe that its new chief executive, Satya Nadella, formerly the leader of the enterprise and services group, was tapped to lead the company earlier this year.

The latest outage follows a widespread service disruption of Lync, Microsoft's online communications service, on Monday.  The company said that the Lync outage was caused by "network routing infrastructure" issues in a statement to ZDNet Microsoft reporter Mary Jo Foley.