Spoofing occurs when an attacker sends emails that appear to come from your domain, tricking recipients into believing the message is genuine. This can harm your brand's credibility, result in data theft, and lead to your domain being blacklisted. Implementing measures like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) can help prevent spoofing.