What is DMARC and why do Gmail and Yahoo require it?
DMARC tells receivers what to do with mail that fails SPF and DKIM, and sends you reports about who is sending as your domain.
DMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS TXT record published at _dmarc.yourdomain.com. It links SPF and DKIM to the visible From address (“alignment”) and tells receiving mail systems what to do when a message fails: nothing (p=none), send it to spam (p=quarantine) or reject it (p=reject).
Why it matters now
Since 2024 Google and Yahoo require bulk senders to publish DMARC, and Microsoft followed in 2025. Without it, legitimate mail is increasingly filtered and your domain can be spoofed freely.
A minimal record
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com
Start with p=none and reports, fix every legitimate sender until reports show alignment, then move to quarantine and finally reject.
Check yours
Use the DMARC Lookup to validate your record and the generator to build one.