How do guests or users who do not register on my forum send me, PM? This is some kind of spam. How do I prevent guests from sending a PM if they do not have a forum registration?

You will have activated the contact button, in the footer links, any message there comes to you as a private message

Hello @smurfavr

In addition to what @Jucarese has said, you need to understand that the PMs coming from the "Contact" link will only be sent to the administrators of the forum. With that being said, there's no way a guest will be able to spam a regular member. The "spam" will just get to the admins

Best regards.

Thanks. Solved.