Preventing non-human interaction (NHI) during email signup and confirmation involves several layers of defense. Techniques include multi-factor authentication (MFA), honeypot fields, robust email validation, email verification services, confirmed opt-in (COI) processes, Javascript challenges, progressive profiling, custom fields, and email authentication protocols (SPF, DKIM, DMARC). These methods collectively aim to distinguish legitimate users from bots by requiring human interaction, verifying email validity, and analyzing behavior.