[jmb99]

For the “least painful” self-hosted email setup, you can’t be hosting on an IP in a subnet that’s ever sent spam, if you want to avoid being blackholed occasionally. This means you can’t have an IP allocated to you by a hosting provider, or a residential ISP, or a “business” ISP, or any cloud provider. That leaves very few options.

Note that I am speaking from personal experience here. I have been self-hosting email for over a decade, from the same IP, with (roughly) the same DNS records. Occasionally, for no reason, I will end up on the global spam list for Gmail, Outlook, or iCloud - never more than one at the same time, and never with a discernible reason. The best I can figure is that the IP is allocated to me by a hosting provider that occasionally sends out spam from its subnet (aka any hosting provider that doesn’t block smtp). I have also tried self-hosting a different mail server from a variety of residential IPs in different cities and countries, and ran into the same problem.