Sign In as Alias - Question

Sign In as Alias - Question

Hi there,

I am really new to Zoho, but already have a question ;)

At the moment I testing around a little bit wit all the features and setting possibilites. I have a Subdomain with 2 Users (Admin and User), the user also has an Alias. I saw that die User can login with is Primary Email and also with his Alias into his Mail-Portal. But I want that the Alias can't sing in - is it possible to set up? I searched in the control panel but found nothing. I thought under "User Details" - " Change Login Email IDs" is the right direction , but couldn't change anything there.

Any help would be great :))

Thanks in advande