There are specific settings regarding fetching emails with specific headers (header Precedence: junk or Precedence: bulk) directly in your LiveAgent account under Configuration > Email > Email settings.
If you have enabled these settings, it only enables processing of such emails with the above mentioned specific headers and if those will be fetched into your panel.
Very often these settings can be misleading for our customers and they might think that disabling such a setting will stop fetching spam emails into their account which is not correct.
If you are looking for information on how LiveAgent recognizes spam, you can find it here.