I had to stop using my own domain and fastmail because I lost not one, but two very important job offers due to my emails not getting received. Not spammed, jus

I had to stop using my own domain and fastmail because I lost not one, but two very important job offers due to my emails not getting received. Not spammed, just outright not received. I also frequently (30% of the time) don't get "verify your email address" emails from websites these days when using my own domain+fastmail. I'm back to gmail and resent having to do so. But it's the only option to not constantly be worried about important emails not making it.