DMARC check
See the domain's DMARC policy, every setting explained, and what to change next.
What DMARC is
DMARC (Domain-based Message Authentication, Reporting and Conformance) is a TXT record at _dmarc.yourdomain that tells receivers what to do with mail that fails both SPF and DKIM: deliver it, put it in spam or refuse it.
It also asks receivers to send you reports, so you can see every service that sends mail as your domain. The usual path is p=none while you read the reports, then quarantine, then reject.
Gmail, Yahoo and Microsoft require DMARC from anyone who sends a lot of mail.
This checks the record in DNS only. To see how a real message from your mailbox is signed and judged, use the complete email delivery test