The email address used to register your AppMachine Reseller account is currently an important unique identifier for your account. Changing the email address of the account itself is not yet possible.

At the moment, the way to switch to a new email address is as follows:

1. Create a new AppMachine account with your new email address
2. Login at http://design.appmachine.com with your old account
3. Open the apps you want to transfer
4. Click "Invite Team Member" in the "Dashboard" section of the menu
5. Fill in your new email address and select the role "Owner"
6. Go to your Account Settings and click on "Become a Reseller," complete all the steps
7. Cancel your old reseller account subscription. 
8. Publish the apps under the new reseller account once the subscription period of the old subscription has ended.