Many good answers. But I was wondering how you guys appeal to the Big Two (Google and Microsoft) if you end up in either their publicly known or secret spam lists? Especially the latter seems to be a problem despite having set up spf, dkim, dmarc correctly.
That’s why self-hosting is not a decision to be made lightly.
And to be clear, if you are running a business you can be blocked by your customers’ infrastructure even if you are fine with the big boys.
And that can happen if you are not self hosting but not using one of the big providers.