Microsoft is investigating an ongoing Exchange Online outage preventing customers from sending emails and triggering 503 errors on affected systems.
Impacted users report having issues with emails sent from Microsoft 365 environments being returned with “503 5.5.1 Bad sequence of commands” errors.
“We’re investigating an issue where some users may be unable to send Exchange Online email messages due to a recent change to the free/busy infrastructure,” Redmond tweeted.
“We’re identifying a plan to resolve the impact. Further details can be found under EX649175 in the admin center.”
As the company confirmed in the EX649175 ticket in the Microsoft 365 admin center, some users may experience issues when sending Exchange Online emails and see “Bad sequence of commands” errors.
“We’re reviewing service monitoring telemetry to isolate the root cause and develop a remediation plan,” Microsoft added.
“Impact is specific to some users who are served through the affected infrastructure.”
The company has yet to reveal which Microsoft 365 regions this Exchange Online outage affects.
However, based on customer reports, the impact has spread to users in the United States, Europe, India, and the United Kingdom.
Two weeks ago, Redmond also addressed an Outlook.com issue preventing users from searching their emails and triggering 401 exception errors saying, “Sorry, something went wrong. Please try again later.”
In June, Redmond addressed another outage preventing American customers from accessing their Exchange Online mailboxes via Outlook on the web.
This is a developing story …