Hi all.
Thanks for the replies.
I was talking about the individual email accounts where people can select an email to be either white list, or black list.
And in the options section of the horde email account, there is a section for managing blacklist. I see in the links provided in the wiki some instructions to add the *@xxx.com in front of the domain and this should blacklist any emails from xxx.com from what the wiki says, however I'm not sure this only applies to the server complete database blacklist as described in the wiki or can the format of *@.xxx.com also work in the blacklist of the user accounts in the manage blacklist section in horde ?
I've put the * infront of those that i want black listed, however this may not be the way to go