Users in several different countries began complaining on Twitter about problems using the services shortly before 9 a.m. ET, and Microsoft posted a notice at 9:49 a.m. on its service status site confirming a problem with Outlook.
"We're having a problem accessing email. You might not be able to see all your email messages," the post said.
A notice posted 10 minutes later confirmed, "Services such as Hotmail, Messenger and SkyDrive are experiencing technical difficulties. We appreciate your patience as we work on the problem."
As of 11:40 a.m., the service status site reported that Microsoft Account, Messenger and Calendar were running normally. However, Outlook, People and SkyDrive were not working.