I am trying to create a new outlook account name but it always  gives error

"what_ever_entered"@outlook.com isn't available.

I have tried different combinations like appending and pre-pending account name with number ,combo of numbers and underscores etc.
 But it always ends up with the same error .

I am sure there is some problem with the sign up system as some of the accounts I tried I m sure are not taken and I even tried sending mail on those accounts and got delivery failure error.

Some accounts I tried

*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***