My hunch on this was that there probably was a misconfiguration with whatever service they're using to send out emails. If they don't have the sending domain w

My hunch on this was that there probably was a misconfiguration with whatever service they're using to send out emails. If they don't have the sending domain whitelisted with whatever service they're using, it can look super fishy (or phishy!). I'd be really, really surprised to find out that Google's automated AdSense ad quality tools are in any way tied to their email quality tools.