Try as much as possible to make your email hidden from the public, secondly if you can go through your settings and restrict who can send you PM and make all newbies unable to do so, all these will help you avoid receiving any unsolicited messages on your inbox, and in case of the ones that manage to escape and still sent you one, once you see them, ignore the user and delete the message, don't accept anyhow inbox in the name of being the same forum user, you cant trust people you see on proxy, they may have shady intentions.