[panny]

>new servers would be online somewhere else within hours of it going down

Yeah, no that's not how it works with email. You have to build reputation for weeks or receivers throttle you.

[kassner]

It is pretty much unacceptable to have a domain bouncing emails, so I’d be out of the provider before the MX TTL even expires.

For outgoing emails, reputation is a huge issue, but at the same time it’s also fairly trivial to set up a (different) 3rd-party (gmail, outlook, sendgrid, whatever) with previous reputation so you can get back communicating.

[finaard]

I'm not running a spam business. I've been operating my own mailservers (and related infrastructure) for more than 25 years now, without issues.