To blacklist/whitelist a domain in AntispamEurope, you will need to add the symbol @ in front of the domain name.
If you don't add the symbol @ in front of the domain, the blacklist/whitelist will not be effective.
Refer below screen captures:
Without adding the symbol @ the email will be delivered as per normal without being blacklisted:
The email delivered without being blacklisted:
It will be effective once you put the symbol @ in front of the domain:
The domain name is blacklisted:
User-bl means the domain is blacklisted.
In additional, if you check under Blacklist/Whitelist in the Control Panel, it will show the domains as per below without the @ symbol. If you are not sure whether it is correctly saved, you may remove it and add again with @ symbol.