Outlook saw a significant spike in user reports on Down Detector, which is one of the first signs that something is wrong with the massive email service. Users around the world reported problems, and the outage raged on for more than four hours.
The outage kicked off around 6:30 a.m. Eastern, but spiked as east coasters started to log on around 9 a.m. Reports didn't start slowing down until closer to noon, though it had a long tail.
