DomainCanary is a DMARC monitoring service. It collects the aggregate reports that mailbox providers already send about your domain, and turns them into a readable weekly summary with alerts for new senders and authentication failures.

We maintain dmarc-rua, the DMARC RUA aggregate report parser that powers our ingest. It parses XML, gzipped XML, and zip report payloads into typed records, extracts report attachments from DMARC report email, and runs on Deno, Node, and Cloudflare Workers. It is published on JSR as @domaincanary/dmarc-rua.