There are three levels of anti-spam protection available for publicly visible forms, such as the Contact Us and Registration forms. A form submission is never silently rejected. Rather, an error message is displayed asking the user to try again if the submission is classified as spam.
None: No anti-spam checks will be performed on form submissions.
Simple: Some basic checks are performed. Form submissions with email addresses that are not well-formed, or that have an excessive number of URLs, are rejected.
Advanced: (Requires an internet connection). Performs additional checks to determine whether email addresses are real, or contained URLs are blacklisted.