Private Blacklist Filter not working

Hi there

We have a number of domains set under the Private Blacklist filter, but some (certainly), are not being filtered and returned.

I am assuming that each domain entered is separated by a carriage return as this works for other multiple entries?

Private Blacklist Filter - Enabled

Desired Result - Log and reject message

Custom SMTP error message - Your message was rejected as spam.

What steps can we take to correct this?

Thanks