When setting up a DMARC policy for an organization, is it important at all to have SPF alignment?
I've gathered that:
- Most email service providers support DKIM for a custom domain.
- Not all email service providers support SPF for a custom domain. Typically these would have passing SPF records for their own domain, but this won't align with the from address.
- With SPF it's easy to run into DNS lookup limits. With DKIM this isn't the case.
- Some "Forwarded emails" such as via mailing lists often have failing SPF, but still passing DKIM. Others rewrite the From field completely to avoid DMARC issues.
Given the above, is there a good reason to have SPF alignment at all? Or is DKIM alignment + a DMARC policy always sufficient?
Note: I'm not suggesting not having an SPF policy at all for the custom domain. Just using the external service provider's domain for the Return-Path instead of the custom domain, and therefore not having SPF alignment.
So in this case we'd have:
From: [email protected] Return-Path: [email protected] (not aligned) DKIM-Signature: d=my-domain.net (aligned) Received from: IP belonging to service-provider.net, passing SPF for service-provider.net.