It was like the 1980s again in offices across the country Tuesday as a widespread outage of Microsoft’s e-mail services for businesses gave workers no choice but to pick up the phone or wander over to their colleagues to chat in person.

Kevin Watson, who runs a political consulting firm in San Clemente, Calif., uses Google for his personal e-mail but, like many in the business world, relies heavily on Microsoft Outlook to stay in touch with clients. His e-mail service was out for more than half of the workday, and he began receiving e-mail only in the afternoon — about five hours late. He worried all day that people were trying to contact him.

“I’ve been picking up the phone and calling my most important clients,” he said. “You can’t stop because there’s no e-mail.”

It’s impossible to imagine the modern working world without an inbox flooded with too many e-mails. Yet during a long window Tuesday for many Outlook users, there was silence.

Microsoft confirmed the outage, but throughout the day the company declined to offer details about the size and scope of the problem. By about 6 p.m., the company said it had resolved the e-mail issue and that users should see their undelivered messages hit their inboxes soon. Later in the evening, the firm said the problem affected only customers in North America, but it still gave no answers on exactly what had happened.

“We sincerely apologize to our customers for any inconvenience this incident may have caused,” Microsoft said in a statement.

The outage threatened to ding the reputation of the company’s marquee business product — Office 365, which offers Outlook — just as Microsoft is trying to prove it can help clients more easily share their documents and messages over the Internet. Office 365 has added online features to respond to the exploding popularity of the Google Docs suite of online products.

Without e-mail on Tuesday, frustrated Microsoft users turned to another modern medium for airing complaints: Twitter.

“Dear @Microsoft: So, exactly how does your cloud computing and Office 365 email being down all day help work productivity? I’m confused,” tweeted Scott Leadingham around 11:15 a.m.

“We are sorry for the experience brought to you,” the company’s Office 365 feedback tweeted to Leadingham, who responded to Microsoft, “I’m sorry, too, that I’m forced to use your product.”

Microsoft’s Twitter feed for its Office 365 product was flooded with other frustrated messages from users asking for answers, to which the company responded that it was still looking into the problem. (This being Twitter, not e-mail, the notes were limited to 140 characters.)

Outlook may not be the e-mail service of choice for many individuals, but it has long dominated the business world and been the product of choice for businesses looking to serve an estimated 50 million employees using cloud-based office products. Nearly 60 percent of Microsoft’s global revenue comes from business users.

And e-mail itself has been part of the business landscape since the early 1990s. By 2012, the average American worker spent 28 percent of the day answering or drafting e-mails, according to a study from the McKinsey Global Institute.

“We take it for granted,” said Martin Irvine, founding director of Georgetown University’s Communication, Culture and Technology graduate program. “In an outage, it’s like: ‘Oh my God. You may have to do things the old-fashioned way!’ ”

Some people such as Watson refused to abandon the medium altogether, turning to Google’s Gmail service — probably not the outcome that Microsoft was hoping for.

“This technology seems so transparent until it breaks. E-mail is like a black box. We have no idea, from one end to the other, how things work. You see what goes out and what goes in,” Irvine said. “We may never know what happened — unless Microsoft tells us or a smart hacker gets involved.”

The problems were particularly bad Tuesday for small-business owners and remote workers who rely heavily on e-mail for fast communication with clients and co-workers. And they seemed to have affected users from California to Massachusetts and at firms of all sizes, including The Washington Post.

Early Tuesday, Pam O’Brien, executive editor of Fitness magazine in New York, received an ominous call from her publishing company: E-mail is down, the automated voice said. Communicate another way.

O’Brien scrambled to reach her fashion director. A cover shoot was scheduled that morning in a Manhattan studio. Were her questions caught in cyberspace?

“I called and called her — but her phone was dead — so she called me from someone else’s,” O’Brien said, laughing. “It was more complicated than usual, but it was nice to have a real conversation.”

E-mail tends to chain those who depend on it to an office, O’Brien said. The extra human interaction may be good for your health. “Today we were getting up and moving around much, much more,” she said, “which aligns with the mission of this magazine.”

Microsoft has been pushing companies to adopt its Office 365 cloud services, promising that moving to the cloud will make workers more efficient, because they can reach their e-mail or other service from anywhere.

Bill Galeckas, who works for Akuity Technologies in Auburn, Mass., helps companies move their systems over to cloud services, including Microsoft’s. But on Tuesday, he had to halt one such migration while he waited for more information on what was going on at Microsoft.

As a fellow IT guy, Galeckas said he was sympathetic to Microsoft’s plight but added that the company could have been more transparent in explaining either what was happening or being frank about not knowing.

And, of course, he felt bad for his client.

“Their first day of getting to the cloud was not as good as they had hoped,” he said.

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