I have been largely successful in blocking them on 'MUD in recent months. Email me and I can forward some of my settings.
Login Spaminator
Registration Spaminator (which BTW auto-blocks over 200 attempts daily)
Signup abuse detection and blocking (with some aggressive settings)
Requires daily reviews of the Spam Triggers log, manually checking any Registration Strings that include "Africa/Algiers"
New registrations frequently remain stuck in the Approval Que for a day or three to monitor their IP history. In EVERY case, one of their recent IP's is from Nigeria. There are also a number of consistencies in their registration emails and usernames.
I gave up on Stop Forum Spam - waste of time.
BTW: I've put a warning notice at the top of MUD Classifieds to an Announcement thread. Reset the "dismissal" notice every few months so members remember to read it again. Only shown to logged in/approved user accounts, one more hoop for the scammers to get thru before they can easily find it
Edit: I've been monitoring new users and their activity. A sizable number joined to contact a Vendor about a product. "Blocking" new registration PM permissions (super simple via Usergroup promotion settings) means those new members need to post 5 or 10 or 50 "junk" posts before they can contact a Vendor. IMO, not a great solution. Signal to noise ratio is already challenging enough.