Where is it hosted? Isn’t the primary issue being blocked by the major providers due to spam filters?

I have used Mailinabox on a Hetzner server for about an year. My email delivers to all the major providers. However, small providers will occasionally block my email. So I continue to use my Gmail address for now.

With small amounts of evidence, I think if my contacts on those providers email me first, and I reply to those emails, then my domain is not blocked.

server4you.

there is one blocklist im aware of that simply categorically blocks all their IPs, but thankfully none of the "big tech" players use it, so its really of no consequence to me

How do you make sure your emails don't end up in spam?

That's a recipient's problem.

That's my current approach with Outlook's IP block blacklists.

i just have spf+dkim, nothing fancy

For me, the issue wasn't that I had to fix it frequently, but that when I did it was urgent, stressful and disruptive. Eventually the VDS I was renting had a fatal HD crash and I gave up.

this would apply to any self hosted stuff you rely on, but yeah, self hosting is not for everyone

Agreed. Salient.