[ForceHSS]

You are wrong if you read it, it says
Note that partial email addresses are matched from the end of the address unless you enable 'Aggressive Email Banning' below. Therefore if you ban @example.com you will ban user@example.com, but if you ban @example that user will not be banned. If you enable 'Aggressive Email Banning', user@example.com would be banned by @example.

If you want to ban them the way you want to
Aggressive Email Banning = Yes