this alias is not allowed

[gw0gvq]

Whenever I try to create an alias in iCloud for  mail I always receive the message, 'this alias is not allowed', no matter what alias I type. I wonder if anyone else has this problem and how doo I rectify it please

 

[maflynn]

What's the alias you're trying to create, maybe its already used/reserved.

 

[gw0gvq]

What's the alias you're trying to create, maybe its already used/reserved.

I've tried several but all come back with same message