The postmark-mcp incident exposed a new category of threat: malicious MCP servers silently exfiltrating emails at scale. Learn how AI supply chain attacks target email infrastructure — and how DMARC and email authentication protect you.

Learn how to add an IP address to your SPF record correctly. Includes syntax examples, provider-specific steps (Cloudflare, GoDaddy, Route 53), an include vs. ip4 decision guide, and a post-setup validation checklist.