The software company stated that it is working to resolve the issue and that no other services appear to be affected at this time.
The outage began at 9 a.m. on Tuesday, June 21, and is believed to have affected users in Europe.
Some Outlook users, according to Microsoft’s own service status website, “may be unable to access their mailboxes via any connection method” and may experience “delays sending, receiving, or accessing email messages.”
“We’re continuing to analyse service monitoring telemetry to identify the next troubleshooting steps to mitigate the impact,” Microsoft said in a statement on the site.
“We’ve identified that our traffic management infrastructure is not working as expected,” Microsoft said in an update.
“We successfully routed traffic to an alternate traffic management method, and service availability has improved since this process was completed.”
According to the website monitoring service Down Detector, affected users are receiving messages indicating that they are unable to connect to a server and are having difficulty connecting to the service from a variety of devices.
The monitoring service reported that reports of problems began around 9 a.m. on Tuesday (June 21).
However, the outage appears to be unrelated to an issue at Cloudflare, which took a large number of popular websites offline earlier Tuesday morning.
Cloudflare stated that the issue has been resolved.