Thousands of Microsoft webmail accounts were temporarily emptied of stored emails following a server error at the company during the Christmas and New Year period.
According to the US software vendor, more than 17,300 Hotmail accounts lost all of their email content as a result of an issue in "mailbox load balancing between servers".
The problem began on 30 December, and upon logging on to an affected account, users were said to have been presented with Microsoft’s ‘Welcome to Hotmail’ email. This message is sent immediately after a user signs up to the email service.
"Customers impacted temporarily lost the contents of their mailbox through the course of mailbox load balancing between servers," wrote Chris Jones, corporate vice president for Windows Live, in a company blog post. "As with all incidents like this, we will fully investigate the cause and will take steps to prevent this from happening again."
Microsoft says that the problem was resolved and all affected accounts’ emails were restored by 2 January 2011.
In December 2009, an official blog post by Microsoft revealed the business continuity precautions its applies to Hotmail. The post revealed that the company maintains four different instances of each email server to reduce the risk of data loss, and operates a round-the-clock emergency response team, with engineers able to respond to any issue "within minutes".
A separate post explains that the load balancing systems that support Hotmail "ensure that storage, CPU, memory, and networking demands are distributed over the entire network of servers".
Microsoft’s cloud-based services have suffered their share of availability issue. In October 2009, a server failure at subsidiary and mobile device vendor Danger caused users of one of the company’s handsets to irretrievably lose all remotely stored contact, photo and calendar data. In August last year, the company’s BPOS suite of cloud-based productivity applications suffered from "intermittent access" for North American users for a number of hours.