What is a DMARC aggregate report?
When your domain publishes a DMARC record, mailbox providers such as Google, Microsoft and Yahoo send you a daily summary of the mail they received that claimed to come from your domain. These aggregate (RUA) reports are XML files, usually compressed as .gz or .zip.
Each report lists the sending IP addresses, how many messages each one sent, whether those messages passed SPF and DKIM, and what the receiver did with them. Reports contain authentication results only, never the content of your emails.