I have also send you an email about this. You should be able to change the email address for the forum account in the profile settings in WordPress. You can also adjust the mail for the shop in the account settings. When it comes to the Max2Play licence, we can only offer you to use a licence code as a new licence instead of your email address.
If you change the licence in the Max2Play web interface, this should have no effect on the Squeezebox server.