Currently that's not possible unless you have business internet.
Basically ISP can mark whole IP ranges as residential, so any email sent from those is marked as spam no matter how you set it up...
It's cheaper to pay Google or similar $6 per month and avoid the hassle of locally hosted mail server.
There's a bad ZFS corruption that applies to certain pools created with ZFS 2.1.x+
Maybe you're hitting it?
NOTE: It's under extremely specific conditions, there's no need to panic...