FYI, exact email I received, a little absurd if you ask me:

Hello, [name]! If you received the "Insecure Alias" error, then it is because aliases will no longer work for wallets which have no email account associated with them. This has been implemented as an extra security measure, and I'm sorry for any inconvenience this may cause. If you do not know what your wallet identifier is, then we can help you recover it. We need at least two of the following to find your wallet identifier - your alias, the email address you used to create the wallet, or the IP address you used to create your wallet. As a last resort we may be able to track down your identifier if you provide your password and the date you created your account. Thanks!