https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/use-dkim-to-validate-outbound-email?view=o365-worldwide

dkim

https://protection.office.com/dkimv2

cname: selector1._domainkey → selector1-##domain-at##._domainkey.##tenant##.onmicrosoft.com cname: selector2._domainkey → selector2-##domain-at##._domainkey.##tenant##.onmicrosoft.com

dmarc

txt: _dmarc → v=DMARC1; p=reject