MyProBB comes with two lists that can be used during installation to “blacklist” certain things.

One list contains all the freebie e-mail address sites out there ordered by popularity. The list can be used to prevent spammers from signing up.

The other list contains words that are considered to be inappropriate for polite conversation. The “Deny Words” list triggers a moderation status change on posts being made that use the words. This means that messages containing the words will be allowed into the system but will require moderator approval before being allowed to be displayed to other users. Only affects users taken off moderation. So it is more of a “filter list” than a blacklist.