Situation: The client just added one new email address (@B.com) to their domain users and would like to replace old email address (@A.com) with the new email address as AD default login email address. Here is how.
- Login ADU&C.
- Go to Users. Right click on the user and select Properties.
3. Click on Attribute Editor and go to userPrincipalName. Change the default email address from username@A.com to username@B.com.
4. Click OK to save it.
Also please refer to this post:
