I use Fastmail as my email provider. Fastmail provides helpful instructions on how to setup both SPF and DKIM for a custom domain. In spite of properly configuring these, I was surprised recently to see that Google mail was marking my emails as having failed a DMARC check:

I spent some time double checking that my email met the normal conditions for DMARC checks. In my case the From addresses were consistent, and they matched a domain for both the SPF and DKIM check. So, nominally, I am compliant with DMARC expectations.

However, my domain did not have a DMARC policy configured. After configuring a DMARC policy, I found that Google began to treat my emails as passing DMARC:

If you’re encountering the same, you should check that your emails meet the normal DMARC conditions, but also consider configuring a basic DMARC policy for your domain.