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Free tool · no signup
Choose a policy, add the address that should get reports, and this tool writes the DMARC TXT record and the host name to publish it at. It starts you at p=none with reporting on: a safe first record that blocks nothing and shows you who is sending as your domain.
Optional. Only used to show the exact host name for your DNS.
Where aggregate reports are sent. One address per line or separated by commas.
Share of failing mail the policy applies to. 100 is the default and is left out.
Leave on 'same as p' unless subdomains need a different rule.
Relaxed lets a subdomain's DKIM signature count. Strict needs an exact domain match.
The same choice for the SPF domain.
v=DMARC1; p=none
Add it as a TXT record with the host _dmarc. Many DNS hosts want only the part before your domain (for SPF, @).
No inbox for reports yet? Free DMARC monitoring gives you an address to put in rua and turns the reports into a readable page. After you publish, confirm it with the DMARC checker.
Publish p=none with a report address and leave it while reports come in. Fix any legitimate sender that fails, usually by adding it to your SPF record (the SPF record generator helps) or turning on DKIM signing at that tool. When everything real passes, move to quarantine, optionally with a small pct first, then to reject.
Check the result any time with the DMARC checker. The wider setup for cold email is in SPF, DKIM and DMARC for cold email.
p=none with a report address (rua). It blocks nothing, and the reports show who sends as your domain and whether they pass. Microsoft's guidance for complex setups is the same: configure DMARC in take-no-action mode first, then tighten once the reports show every legitimate sender passing.
pct is the share of failing mail the policy applies to. With p=quarantine and pct=25, only a quarter of failing mail is quarantined. It is a way to ease into a stricter policy. It has no effect while p=none, and 100 is the default, so the generator leaves it out.
rua is the address that receives aggregate reports: daily summaries from receivers of which servers sent mail as your domain and how it did on SPF and DKIM. A record without it is valid, but you fly blind. If you have no inbox for reports, free DMARC monitoring on Warmerly gives you an address and a readable page.
DMARC passes only if the domain that SPF or DKIM authenticated lines up with the From domain. Relaxed (the default) accepts a subdomain of it, so mail.example.com aligns with example.com. Strict needs an exact match. Leave both relaxed unless you have a reason.
As a TXT record named _dmarc on your domain, so the full name is _dmarc.yourdomain.com. Publish one DMARC record per domain. Run the DMARC checker afterwards to confirm receivers can read it.
Check any domain's SPF, DKIM, DMARC, and MX records in seconds.
Validate an SPF record: one record, 10-lookup limit, and a safe ending.
Build a valid SPF record from your senders and IPs, with the lookup count.
Look up a DKIM key by selector and check its type, size and test mode.
Look up a DMARC policy, reporting address, pct and alignment.
List a domain's mail servers in priority order and spot a missing or null MX.
Check a domain or mail server IP against Spamhaus, SURBL, URIBL and more.
Scan a subject line and email body for spam-trigger phrases.
Get a day-by-day sending ramp schedule for a new or existing mailbox.
Check text-to-HTML ratio, images, links, and tracking pixels in an email.
Warmerly re-checks SPF, DKIM, DMARC and blocklists on every sending domain daily and warms your mailboxes while it does. Free plan, no card. Paid plans from $19/month.
