Despite the common consensus, self hosting your outbound email it's not impossible to do (*)

bgp.tools has been sending it's own outbound email since day one of having the ability to send email, while i have been doing a migration i have discovered that rspamd (for DKIM signing) was keeping it's own logs outside of journalctl, meaning they never got rotated (grrr)

The upside of this log rotation failure is that I can give you this graph: The total email volume sent per month via bgp.tools

I don't think it has been particularly hard (other than hotmail) to run this, and it means that I don't have to give customer emails to another 3rd party.

I think the only struggle for a lot of people is that it's quite difficult to find "clean" or at least "boring" IPs to send out from. i suspect you probably couldn't replicate these results with Hetzner/Digital Ocean/etc without some serious fighting or luck

(*) unless your service depends on sending to hotmail/live/msn emails, because that shit is impossible