Many DMARC providers give visibility into your outbound email activity, include sources that send on your behalf.
Look at the beginning of your DMARC DNS entry for the part that designates your DMARC Policy with "p=xxxxxxx".
Here is a tool to check your DNS record: http://easydmarc.com/tools
DMARC policies can be 1 of 3 values: None, Quarantine, and Reject. Too many times, we see customers set to a DMARC policy of "p=none" and have been led to believe they have DMARC in place. But please know that this is only an "observation" phase. You are only collecting reports in this phase and in no preventing phishing or Business Email Compromise.
At what policy is your DMARC set? Maybe more importantly, if you are at p=none, does your DMARC provider offer assistance in advancing your policy and at a cost that fits your budget?