It’s a total minefield for me. Something I’ve never really tried to get my head around other than getting something to work (and not necessarily understanding it).
However, the Enom host record editor did not let me add a period to skellis.net “The hostname cannot end with a period (.).” AND @RosemaryOrchard it wouldn’t let me add quote marks to the txt record!
I started working with Enom’s SPF wizard: https://www.spfwizard.net and have sent another version to Mailchimp to likely be returned as an authentication failure in a couple of days time.
Winter is coming. (except in NZ).