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Outlook outage: Microsoft blames European Hotmail downtime on load-balancing fault

Microsoft claims connectivity issues that blighted Outlook and Hotmail users for much of Monday 18 September have now been largely resolved

Microsoft says its online services are back to normal after Hotmail and users across the UK and Europe were left unable to send or receive emails for 12 hours on Monday 18 September.

According to a series of posts on the Outlook service status page, the issue appears to be linked to a fault in a “subset” of its load-balancing infrastructure, which Microsoft said was seemingly experiencing an uptick in CPU utilisation.

“We’ve implemented configuration updates on the affected load-balancing infrastructure, and we’re monitoring the environment while the resulting queue of email messages is being delivered,” the status page added.

During the outage, any emails that users attempted to send were automatically saved to Drafts, and in the early hours of Tuesday 19 September, a backlog of delayed incoming messages started to arrive in the inboxes of many affected Hotmail and Outlook users.

Although the Microsoft service status page says the service is now up and running again as normal, there are numerous reports on Twitter from users who are missing emails sent to them during yesterday’s outage.

Based on the responses of the Outlook Twitter account, it appears to be aware that some users are still missing messages, and says its engineers are still working on restoring them.

“A very small number of messages sent during the incident may be delivered over the next few hours as the last remaining messages are processed,” the Outlook status page added.

Read more about Microsoft outages

  • Office 365 users across parts of the UK and Europe experienced technical difficulties this morning, while subscribers to Microsoft’s free email service, Outlook, have been reporting connectivity problems for much of the day.
  • A Microsoft Azure outage left users across the globe unable to access key services for a couple of hours on 15 September because of a DNS malfunction.

Computer Weekly has contacted Microsoft for further information on the cause of the problems, which coincided with an Office 365 outage that started at around 9am yesterday morning and lasted several hours. At the time of publication, no response from Microsoft’s press teams was forthcoming.

According to Microsoft, has 400 million active users, and was adopted as the new brand name for its free email service in 2013 after a transitionary period that saw users upgraded to a new-look user interface even if they still retained their existing Hotmail account IDs.

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