Either no one checks their email, or you initially registered with your bogus email (which I know many of us do) and you're not getting their messages. Whichever it may be, here's the email that was sent out to all accounts that ran into this security measure:
Bitstamp has detected an increase in the number of reports of phishing emails which were also received by some of our clients. Our technical team responded by examining the threat and setting immediate security measures in place to prevent potential risks.
As a precaution we have also applied this security measure to your account.
If you have received any emails with suspicious content and have opened links or attachments we highly recommend that you immediately contact a computer expert.
While we appreciate that this comes as an inconvenience we are convinced that our security precautions are in accordance with your expectations in keeping your account secure.
If you consider that your system was not affected we kindly ask you to contact
security@bitstamp.net to re-enable the withdrawal function on your account.
Please be advised that Bitstamp will never ask you to reveal your password.
Thank you for your understanding.
Best regards,
Bitstamp Team