Microsoft Azure: Adding user requires more work as expected

Just to try some things in Microsoft Azure i wanted to add an additional user to my test account. But this was not so easy:

Go to "Azure Active Directory" and "Users":

 

 But then:

I thought this is not really a problem, because openesb.eu is my domain, so let's try to verify this one:

The problem is, that i am not able to change this settings. So i tried, if i am lucky, but:

So only way to add users in such a minimal setup, is to add accounts from live.com etc..