I'm not familiar with the Email Deliverability PowerPack but try checking your SPF record on a website like this one: https://mxtoolbox.com/spf.aspx It should tell you WHY your record is invalid. Our SPF record was recently invalid because it had too many DNS lookups (the max is 10). However, it has always said it was verified in Marketo. I think Marketo might just verify that it exists rather than verifying that it is valid. Even though our SPF record was invalid, we didn't notice any deliverability or engagement issues. But we still removed a lookup that we no longer needed because it was added when we were using a different emailing platform. Our record is back to valid now. Hope this helps!
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