Outlook.com partial outage stretches to 20 hours
As of 8 p.m. ET, service to those customers had not been fully restored.
"We have rolled out a fix to address this issue. The fix will take time to resolve and we expect all services to be fully restored by later today Pacific Time," Microsoft said on its system status page Wednesday just after 1 p.m. ET. "Impacted users can continue to access email via Outlook.com and any unaffected client."
The problem affected synchronization -- updating the local client to reflect received email -- and prevented users form sending new messages. Microsoft first acknowledged the trouble around 12:30 a.m. ET Wednesday.
According to Microsoft, the affected email clients included Windows Live Mail, an older program last updated in 2012; the touch-enabled email apps integrated with Windows 8 and Windows Phone 8.1; and Office Connector. The latter, an add-on, is required to receive Outlook.com email in Outlook 2003, 2007 and 2010 (but not the newest Outlook 2013 on Windows or Outlook 2011 for the Mac).
As Microsoft noted, Outlook.com continued to be available via a browser pointed to the service's URL.