DNS Lookups (SPF, DMARC, DKIM) at MXToolBox


SPF Lookup:
---
  TXT Lookup
    i.e.  hotmail.com

DMARC Lookup:
---
  DMARC Lookup:
    i.e.  hotmail.com

  TXT Lookup:
    i.e.  _dmarc.hotmail.com
	
DKIM Lookups:
---

  CNAME Lookup:  selector1._domainkey.<domainname>
    i.e.  selector1._domainkey.hotmail.com
  
  DKIM Lookup:  <domainname>:selector1
    i.e.  hotmail.com:selector1

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DNS Record formatting


SPF DNS Record
---
  Record:  TXT
  Name:  @
  Value:  v=spf1 <include: and/or ip4:> -all
    Rules:  include: = FQDN;  ip4: = IP Address;  Multiple include: & ip4: are ok, seperated by a space
    i.e. v=spf1 include:spf.protection.outlook.com -all
  TTL:  1 Hour (3600sec)


DMARC DNS Record
---
  Record:  TXT
  Name:  _dmarc
  Value:  v=DMARC1; p=quarantine; pct=100; rua=mailto:rua@<<domainname>>; ruf=mailto:ruf@<<domainname>>; fo=1
  TTL:  1 Hour (3600sec)


DKIM DNS Records  (Microsoft 365)
---

Visit https://security.microsoft.com/dkimv2
Enable DKIM for appropriate Domain(s)
Copy the information displayed

  Record:  CNAME
  Name:  selector1._domainkey
  Value:  ???
    i.e.  selector1-<emaildomain-com>._domainkey.<365TenantRootDomain>.com

  Name:  selector2._domainkey
  Value:  ???
    i.e.  selector2-<emaildomain-com>._domainkey.<365TenantRootDomain>.com

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https://dmarc.org/overview/
https://datatracker.ietf.org/doc/html/rfc7489#section-6.1
https://learn.microsoft.com/en-us/defender-office-365/email-authentication-dkim-configure?view=o365-worldwide
https://dmarcian.com/how-to-publish-a-dmarc-record/