Build a valid SPF, DMARC, DKIM or MTA-STS record from a form, then paste it into your DNS. Everything is assembled in your browser, nothing you type here is sent anywhere, including to us. Each generator also has its own page: SPF · DKIM · DMARC · MTA-STS.
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Host names are shown the way most DNS panels expect them. A few providers
want the full name including your domain, if yours shows an existing record as
_dmarc.yourdomain.com rather than _dmarc, use the full form.