Wednesday at 6:00PM, Microsoft reported that issues with Office 365 related to mailbox connectivity have been resolved. Here is the official response:
Final Status: After engineers completed the corrective actions on the remaining mailbox capacity, engineers have confirmed that the service is restored.
User Experience: Affected users were unable to connect to the Exchange Online service when using multiple protocols including Outlook, Outlook Web App (OWA), Exchange ActiveSync (EAS), and Exchange Web Services (EWS). Additionally, affected users were unable to receive email messages.
Customer Impact: A higher than average number of customers reported this issue. Analysis indicates that customers likely had some users experiencing this issue. This event affected approximately five percent of users. For customers on a small portion of mailbox capacity, the majority of users were impacted by this event.
Incident Start Time: Wednesday, July 1, 2015, at 7:05 PM UTC
Incident End Time: Thursday, July 2, 2015, at 12:00 AM UTC
Preliminary Root Cause: A high-level portion of the network infrastructure became degraded, which caused an interruption to Exchange Online connectivity.
Next Steps: The following is a list of known action item(s) associated with this incident. As part of the Office 365 problem management process, additional engineering actions may be identified to improve the overall service.
- Action: Review network routing to avoid communication interruptions related to network infrastructure issues.
A post-incident report will be available on the Service Health Dashboard within five business days.