SPF Misconfiguration: Why Mixing -all and redirect= Breaks Email Authentication

A common SPF configuration mistake involves placing the redirect= modifier alongside the -all mechanism in the same DNS record, which renders the redirect= directive completely ineffective. SPF records are evaluated mechanism by mechanism, and since the 'all' mechanism always matches every sender, it produces a result before redirect= is ever considered. The redirect= modifier is only triggered when no mechanism in the record produces a match, making it incompatible with any record that includes 'all'. Unlike include:, which adds another domain's senders to your own policy, redirect= is designed to fully delegate SPF policy to a central record — useful when multiple domains share one sending configuration. Administrators who want to combine their own IP addresses with a provider's authorized senders should use include: with a closing -all, rather than relying on redirect=.