I would like to suggest that in WH 4.0 under Tools > Update Contact Information that you add at the very least a secondary email contact address. Then when information is sent out or a ticket is replied to it is sent to both those email addresses. That way if the primary email can not receive then the second one would hopefully still get the email.
I want this setup because I often send folks your way and the set up accounts with you but then they want me to help administer their sites. It would be great if I received the emails they get simply because they do not always understand what the email is about. With the new 4.0 system support tickets are sent to the main contact email so if I am reporting via thier account (which I assume is the best thing to do to avoid confusion in domains) I have to detail in the post that it is me and ask that they use my email to reply to. So far this has worked the two times I have done it but I think that is because the technician recognized me and my name and knew I was working on the account.