Since Windows 8, you can log in to your PC using your Windows Live credentials. However, since this is not a local account anymore,
.username won’t work anymore.
If this format is needed, (e.g. RDP login), use:
So if you registered with “firstname.lastname@example.org”, this would be
PS: Yes. you can use your normal E-mail address instead of @hotmail or @outlook, at least that worked 10 year ago
PPS: I’m feeling old now…