It's not self hosted, we're using one of the largest email vendors for ISPs. We used to allow Google to host our mail servers, and saw similar levels of phishin

It's not self hosted, we're using one of the largest email vendors for ISPs. We used to allow Google to host our mail servers, and saw similar levels of phishing getting through although that was several years ago now, and I can only hope they've gotten better at filtering out what actually reaches people's inboxes.