The email address used to register your AppMachine 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"

You can transfer all your apps in this way.

For Resellers, please follow the instructions here.