Lots of websites are using forums software and some of them get a lot of daily contribution of threads and reply by their usernames. It is hard sometimes to manage the forum if there is a lot of spam by bots or humans so to reduce spam without losing users contribution and traffic I want to suggest some tips:
It’s a useful plugin that available for almost all forum software and you can move your forum to another software if it’s not available. It has data of almost every forum bot and human spammer and by using this plugin will block any registration of common spammers. You can also add spam data to their database if you know and want to help others.
Email verification can be useful to stop bots and as we know it is used by almost all big websites. You can give a random password in email instead of a verification link, because it will be hard for bots to break it.
You might need a moderator if you have lots of users daily and it will help to moderate or delete any thread and it will help to reduce spam. Plus, it will save the forum’s reputation.
As we know a lot of spammer have some common intention and they usually come for seo and links so we can use some techniques like disallowing signatures or profile links for new users. We should not limit too many privileges of new users as it could reduce their contribution and make them less interested.
We can use some human verification technique like capchas image verification but a lot of spammers can still break it so instead we can ask some common random questions that can be easily known by everyone.
I hope the above techniques will help to reduce spam on your forums without losing any traffic. You can take any management premium service from an internet firm if you get many threads daily or otherwise use the above tips to fight spam.