DMARC

TLDR edit

You need to have SPF and DKIM properly established first.

(assuming your domain is 'example.com') Publish a DNS TXT record with this label^[1]:
_dmarc.example.com
and this value
v=DMARC1; p=none; rua=mailto:postmaster@example.com;

try http://kitterman.com/dmarc/assistant.html

Background edit

https://dmarc.org/

IETF Specification edit

https://tools.ietf.org/html/rfc7489

Vendors edit

Dmarcian edit

https://dmarcian.com/ is a place where you can get your reports nicely aggregated and reported. See their

video about DMARC benefits
Their project deployment process is spot on. It's a great example of how deploying technology into an organization is more about the people, process and cross-functional training plus 'wiki' knowledge left at the end of the process than it is about the technology alone.
deployment checklist
Inspector: https://dmarcian.com/dmarc-inspector/equality-tech.com
Mission Control is their account 'dashboard'

Tools edit

dig any _dmarc.example.com +trace

References edit

↑ Namecheap has a particular quirk where the 'label' (or host) portion of the TXT record should just be '_dmarc' and their system will append the domain for you.

[1] Namecheap has a particular quirk where the 'label' (or host) portion of the TXT record should just be '_dmarc' and their system will append the domain for you.

[1]