The SPF redirect trap: why -all can make redirect= useless SPF records often look simple until you start combining mechanisms and modifiers. One particularly easy mistake is to write a record like this: v=spf1 include:_spf. google.
Source: [Dev.to](https://dev.to/petr_michal_178dc4f87ad91/the-spf-redirect-trap-why-all-can-make-redirect-useless-3h0f)