guest posts

How to find all guest posts? https://xenforo.com/community/search/member?user_id=0 doesn't work.

I want allow guests to post to a forum, that only allows people (registered and guests) to view their own threads. Mods have permissions to view and reply in all threads. The point of this forum is so people can contact all mods as opposed to a PC to one mod or contact form to one admin. The...