Hushmail is different from all the known public email services for so many reasons, that apart.
You made need to whitelabel the blockchain email address and try again, if that fails you will need to check the settings of the email protocol of your account.
I once use one similar email I can't remember the name, but I notice that they cannot receive all the confirmation links that I need to receive from the sites that I want to receive like forget password and account confirmation, if you notice if you are active in list building service like listjumper they will not go through your email, that is why they only recommend gmail, because gmail can accept all kinds of email that you, expect to receive, that is why I discard this kind of email service.