Hello,
I am trying to create a new account with my new last name because I recently got married. However, When I got to create the account it says the email isn't available. So I thought I had already made it so I tried to sign in with the email address, when I go to sign in it says the Microsoft account doesn't exist. I even tried to add numbers and I got the same situation. I reached out to Microsoft live chat and they stated that for some reason the system was blocking the email address. There is no explicit wording in the email address that would cause the block.
