We recently mentioned that many Hotmail users had their emails disappear over the New Year and now Microsoft has given an official explanation to the situation on the Windows Team Blog. Apparently the issue was caused by an error with an automated script that Microsoft uses to test the service for errors in daily usage. The script is generally supposed to clean up after itself after creating test accounts, but a mistake caused it to jump the test group and go into the actual user accounts.
The good news is that the data is still intact, though if you didn’t log in to your Hotmail account when it occurred, it meant that email messages sent to you during the affected period would bounce back as if the account was shut down. The bug affected over 17,000 users and it’s been said that over 16,000 had their accounts fixed a day after the company begun to address the issue. Microsoft is now splitting its service testing accounts from the set of normal user accounts in order to prevent such an issue from happening again.