Hi Robert,
I’d like to clarify that you want to change the email domain address without losing the data. Is that correct?
To change the email address domain, please perform the following steps:
1. Login to Microsoft Online Portal.
2. Click “Users” under Management panel to show the users list.
3. Select the users that you want to change the email domain. Click “Edit”.
4. Then you can change your email address domain to a verified domain.
Changing the email domain in this way, the data associated with the email address will not be lost.
Note: the new custom domain must be verified.
Thanks,
Kevin Cui