Hi Nettykuss
Thank you for your post and welcome to our community.
The non Virgin Media email address if for security reasons so this is correct process to change this.
This will then be the sign in address.
With regards to linking his outlook account, please follow the below process.
If you want to access your Virgin Media emails from an app, you’ll need to create a separate app password through Account settings on My Virgin Media.
To get the password, follow these steps:
Sign in to My Virgin Media
a. Go to Account settings, then Account details
b. Tap Manage next to Manage your Virgin Media Mail app password under Virgin Media Mail
c. Then, under Virgin Media Mail app password tap Generate new App password and follow the instructions
A new secure password will be generated for you. Your app password can be used for all apps accessing your Virgin Media mail address. If you create a new app password, you’ll need to update all your existing apps with the new password.
We need to give you a separate app password to help make things more secure as IMAP and POP don’t support extra protection steps, like Multi Factor Authentication.
Remember that this password is separate from your sign in details for My Virgin Media (or any Virgin Media apps). So, if you need to check your Virgin Media Mail emails through My Virgin Media or at mail.virginmedia.com, you'll still use your My Virgin Media password.