I use a combination of these two mods...
https://vborg.vbsupport.ru/showthread.php?t=131568
https://vborg.vbsupport.ru/showthread.php?t=124828
one allows you to set a list of keywords that will automatically trigger any post or thread with those words to be moderated (unless the member has more than the amount of posts you set in the mod)
the other is a replacement i use for the captcha system...because i don't like those stupid pictures...to hard to read and turn some people away...so instead guests that want to post have to answer a really simple question (which a spam bot can't do) before they are allowed to post...
it works well for me