DMARC: meaning and how it works
DMARC: the meaning
DMARC stands for Domain-based Message Authentication, Reporting and Conformance. It builds on SPF and DKIM: DMARC determines whether suspicious mail is allowed through, ends up in quarantine or is rejected, and sends you reports about who is mailing on behalf of your domain.
Explanation
Without DMARC, a recipient doesn't really know what to do with a message that fails the checks. With DMARC you give clear instructions and keep sight of misuse. For small business owners that's a solid step against phishing using your own domain name. If you want to set it up, read DMARC explained.
Example
A scammer sends mail that appears to come from you@yourbusiness.be. The message fails SPF and DKIM. Your DMARC policy is set to "reject", so the receiving server doesn't let the mail through. Your customers never even see the fake message.
How to start with DMARC
You begin with a cautious policy that blocks nothing but does collect reports (the "none" setting). That way you first see who is all mailing on behalf of your domain, without any risk that legitimate mail is dropped. Once the picture is clear, you tighten it step by step to "quarantine" and eventually "reject". DMARC only works well if SPF and DKIM are already set up correctly, because DMARC builds on the outcome of those two checks. So take that order: first SPF and DKIM, then tighten DMARC.
Related terms
- DMARC explained
- What is SPF?
- Back to the glossary
Want to protect your domain? DMARC explained shows you how to start calmly.