Microsoft Office 365: January 18 and February 22
Some Office 365 users were painfully separated from their cloud-based email accounts for many days, starting on Jan. 18.
Microsoft blamed a buggy software updated, but its first attempt at a fix didn’t hold -- another salvo of email failures riled customers five days after the initial outage was reported. Problems with the cloud productivity suite’s email services persisted for longer than a week in some cases. While not all Office 365 users suffered downtime, those affected had a large number of users, Microsoft confirmed.
About a month later, some Microsoft customers in Europe had a rough time accessing their email from their mobile phones, or had to endure delays as they tried to log in to Office 365 services through the web portal.
Microsoft said both outages occurred because infrastructure components became degraded due to heavy resource demand from users.