Microsoft has said it has fixed a problem with its Windows Live Hotmail service that temporarily deleted the email of more than 17,000 users.

The trouble began on 30 December when the email in 17,355 accounts disappeared. On Monday, a Microsoft executive wrote that the company had identified the technical glitch and restored email to the affected accounts by Sunday night.

"Customers impacted temporarily lost the contents of their mailbox through the course of mailbox load balancing between servers," wrote Chris Jones, a corporate vice president with Windows Live Engineering, on a company blog.

"As with all incidents like this, we will fully investigate the cause and will take steps to prevent this from happening again. We’re very sorry for the inconvenience this may have caused to you, our customers and partners."

Users created a Facebook group that outlined their problems with Hotmail. Some users reported that their email had indeed been restored by Sunday night, but others noticed inconsistencies.

Several people wrote that their emails had been restored but that they were missing new ones sent since December 30, the day the outage occurred. Company officials wrote on another forum that the issue was resolved by Sunday night.

Microsoft uses its SQL Server to manage Hotmail in what it says is the largest deployment of its product in the world, using tens of thousands of SQL databases.