Is it to keep the spammers at bay?

If so, if we only allow registered users to create and reply to posts, could we turn the referrer check off, or are there other issues?

tia

It's to keep someone from using a bot or spamming script from flooding your board with posts from another domain.

If you turn it off you could still get hit from a registered user, but I think a registered user would be less likely to spam your board.

I only allow registered users, and I set mine to off because some firewall programs strip the URL from outgoing http headers and a few users were complaining that they could not post.

Thanks for the confirmation.