Rules and blacklists

I am not sure what the point is of setting rules and using blacklists if they don’t work. For instance, I have a domain blacklisted, applying the blacklist does nothing, at all. All emails from the blacklisted domain still remains.

The same happens with rules. I have a rule set for a specific domain / email address. Applying the rule, again does nothing. Surely, a rule should operate on existing emails?

I have also tried specifying a specific email account for the rules - again, zilch. No effect whatsoever.