Once you have DKIM, SPF, SenderID and so on in place, you can determine a proper DMARC policy for your needs and publish it in your DNS.
You'll receive forensic or aggregate reports directly and they will tell you if other people (spammers, phishers, etc.) are potentially trying to use their domains for spam / phishing.
The policy itself lets you tell email account providers (like mail.ru) what authentication the messages you send are supposed to use (i.e. you can declare, for instance, that all messages should be SPF compliant and have a valid DKIM signature).
The policy also says what should be done with messages that don’t match the rules (monitor/report, quarantine or reject).
All in all:
Since this is specifically meant to deal with invalid messages, this means these messages never come from Ofsys (if all is configured properly), so we are not involved in creating, puiblishing or monitoring that policy.