"This email address is part of a reserved domain"

[PhilDawson8270]

I use a personal email to login to windows, it doesn't care... e.g. firstname@othername.net !!

But if you did firstname@othername.net to log in to Windows, this becomes the Microsoft Account. If you add a 2nd Alias (account) to the outlook or mail software in Windows, that is firstname@hotmail.com it won't like it, as this is also a Microsoft Account, so you're trying to use 2 at once.

 

[fossyant]

But if you did firstname@othername.net to log in to Windows, this becomes the Microsoft Account. If you add a 2nd Alias (account) to the outlook or mail software in Windows, that is firstname@hotmail.com it won't like it, as this is also a Microsoft Account, so you're trying to use 2 at once.

Never tried it. Don't use the Windows 10 to access emails anyway - We use phones and the Windows 7 machine to retrieve emails. The 3 Win 10 machines don't log into my or the missus emails. Used for cloud backup actually. On the Win 10 machines, I use web mail as the machines are used by the kids.