So basically a while ago I created a Microsoft account for my Windows 8 computer, and I used my Gmail email address.

Shortly afterwards I discovered that it had created a form of email account, with the exact same email address as my gmail account. I can send emails using it (but it shows up with a scam warning), but anytime I reply to those emails it goes to my gmail account.

Recently, just for fun, i logged in and saw this:

They weren't in the Junk folder, but the main inbox. aside from the "welcome to" and "welcome to your new email account" emails, they are all of the emails.

Technically this account should be impossible to access. So how the heck am I getting spam?