A spambot appears to have found a way to post without having a registered username, and there is no record in the mod log of the post being approved (I have the first ten posts to require mod approval).
Is the username in the post hyperlinked or not? A hyperlinked username would belong to a registered user. Non-hyperlinked means it's a guest post (not registered). If it's a guest post then maybe your Unregistered group has posting permissions...
Is the username in the post hyperlinked or not? A hyperlinked username would belong to a registered user. Non-hyperlinked means it's a guest post (not registered). If it's a guest post then maybe your Unregistered group has posting permissions...