Got this in an email:
This is an automated notification sent from our account security system. You logined your account successfully at 4:27 on April 26th form the 125.21.167.* range, but our system shows the 125.94.112.* IP range exists a large number of hackers. As too many customer complaints, the 125.19.169.* IP range has been blacklisted. We are concerned about whether your account has been stolen. In order to guarantee the legitimacy of your account, we need you check your account status here as soon as possible. If you have any questions, please visit :
Account security is solely the responsibility of the accountholder. Please be advised that in the event of a compromised account, Blizzard representatives will typically lock the account. In these cases the Account Administration team will require faxed receipt of ID materials before releasing the account for play.
Blizzard account system