Troubleshooting DMARC failures requires a multifaceted approach involving technical configuration, proactive monitoring, and policy implementation. It begins with meticulously inventorying all email sending sources (ESPs, third-party services) and their authentication settings (SPF, DKIM). Implementing a DMARC vendor streamlines this process by providing reports, dashboards, and automated alerts to identify unauthorized senders, misconfigurations, or potential spoofing attempts. Understanding and addressing the underlying causes of SPF and DKIM failures, such as SPF PermErrors, insufficient DKIM key sizes, or DKIM verification issues, is critical. Correct DMARC record syntax, SPF flattening to prevent lookup limits, and proper reverse DNS (PTR) record configuration also contribute to successful DMARC implementation. Finally, initiating a 'p=none' DMARC policy allows monitoring and issue resolution before enforcing stricter policies that could inadvertently block legitimate email. DMARC alignment, requiring both SPF and DKIM to pass and align with the domain, is a key aspect of the process.