Hi,

Our company has Exchange server and we want to implement DMARC as a receiver. As below link says receiver like mailbox provider should implement DMARC themselves, we use our company server as mail server so we don't even know whether DMARC is implemented as a receiver. Please let me know how can I implement DMARC in our Exchange server.

http://dmarc.org/faq/end-users/#u_2

Hi,

DMARC policies are published in the public Domain Name System (DNS), and available to everyone. Because the specification is available with no licensing or similar restriction, any interested party is free to implement it.

Before deploy DMARC in your environment, we must collect a list of all your companys authorized email domains, including external domain.
Then register DMARC DNS record for all of these domains. For DMARC to work correctly, you need to have SPF records setup in the correct way.

More details about Using DMARC in Office 365, for your reference:
http://blogs.msdn.com/b/tzink/archive/2014/12/03/using-dmarc-in-office-365.aspx
http://blogs.technet.com/b/eopfieldnotes/archive/2015/02/26/using-dmarc-to-prevent-spoofing.aspx