spam settings

Hello! I'm having quite a lot of accounts created that do not actually post threads or post on other members threads but instead an account is created and a link usually pointing towards another site selling drugs or supplements you know the usual stuff you'd see if a spammer/bot would post in...

I have entered an Akismet API key for the forum. No problem with that. Question--does Akismet check every forum post as it is made, or only the first X number of posts (as set by "Maximum Messages to Check for Spam" in the admin settings)? I could see bumping into my top monthly limit on the...