Now that we don’t have that footer link on the bottom of the email message to put a message on the black list, so
it’s very difficult to do so and almost impossible if we’re talking about the user’s will, why not to give user
the possibility to find that bad message in the message tracker and have the possibility to put it on the
black list with a just click?
That would make things easier
What do you want to blacklist? Email address, whole domain? Not easy if a user has to decide.
And I see another problem which can happen through other circumstances too. If you change an email (=adding a footer) then you break this unity. So in some cases this mail will be tagged as 'security broken'.