<spf> alignment for dmarc

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spf domain alignment for dmarc

DMARC is an email authentication standard, developed to combat spoofed domain mail.
For domain alignment it requires that:

   when a sender authenticates their email using SPF and/or DKIM,  
   at least one of the domains must align with the sending From domain

To get it within SPF (Sender Policy Framework), you deal with two domains:

  • the sending From address, that is visible to the recipients
  • the Mail-From address (also called “envelope sender” or “return-path”), that is hidden

DMARC allows two types of SPF alignment: relaxed alignment and strict alignment.
If you do not specify strict alignment, relaxed alignment is assumed as the default.

relaxed alignment

With relaxed alignment, only the root domain of the Mail-From address must match the root domain of the From address.
Relaxed alignment allows any subdomain to be used and still meet the domain alignment requirement.

example:

  • if your Mail-From domain is mail.abc.com and your From domain is abc.com,
    your email will pass SPF alignment (the root domains “abc.com” match)

  • if your Mail-From domain is abc.mail.com and your From domain is abc.com,
    your email will NOT pass SPF alignment (the root domains “mail.com” and “abc.com” do not match)

strict alignment

With strict alignment, the domain of the Mail-From address must match exactly the domain of the From address.

example:

  • if your Mail-From domain is mail.abc.com and your From domain is mail.abc.com,
    your email will pass SPF alignment (the domains “mail.abc.com” match)

  • if your Mail-From domain is mail.abc.com and your From domain is abc.com,
    your email will NOT pass SPF alignment (the domains “mail.abc.com” and “abc.com” do not match)

last updated on July 28, 2020


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