XF 1.4 Require first post of every member to be manually accepted


I'd like to have the feature to require the first post of every member to be accepted by a moderator, this is to prevent spam, I have a lot of spam bots spamming my forums and I need to stop this.
If there are any functions or addons for this, please tell me.

Thank you in advance!

Best Regards,
Bas de Vet
@Brogan is there an option to set max posts under moderation per user?
So if I have 5 posts under moderation, I can't post a 6th one until one of the posts under moderation gets accepted?