updated 06:27 am EDT, Mon August 19, 2013
Exchange ActiveSync issue flooded servers, system changes made
Microsoft has issued an apology for the three-day outage of Outlook.com and other online services, at the same time as explaining what caused the issue in the first place. A caching service that works with devices using Exchange ActiveSync caused the outage, with its failure and subsequent flood of traffic stopping access to Outlook, SkyDrive, and contacts list for some users.
The apology on the Live Status dashboard, spotted by The Next Web, mentions that the original issue was solved "within a few hours of the initial incident," but a "significant backlog" of requests forced Microsoft to open up access to the service slowly, ending up with a full three-day wait for some users. The company states that it has made two key changes in order to "harden" its systems, including increasing network bandwidth in the affected area, and altering how errors are handled for Exchange ActiveSync devices, and will continue to monitor the system for any further issues.
The status update concludes with "We want to apologize to everyone who was affected by the outage, and we appreciate the patience you have shown us as we worked through the issues."