Dont use a random IP to host? I use fastmail, even though they're trying to convince me that I need to pay ~$45 now instead of $5/year.
And they sent me an email explaining how grateful I should be, that I'm grandfathered in to being able to use my own domain on a "plan" they dont even offer., in a plan that didn't offer custom domains.
Well how'd I get all that then? I signed up for fastmail explicitly because $5/yr for custom domains.
Anyhow if you pay a host you're probably fine. Or find someone with an old /24 thats had a /31 or /32 unused for a long while, and no other black marks against the /24. And use that IP, set up demarc and all the other new email DNS stuff.
I migrated from Fastmail to Runbox in 2017, having been a customer with the former for four years, after I filed a ticket and the Fastmail CEO responded with such obnoxious belligerence that I swore off doing business with Bron or his company ever again.
The ticket began with a question about whether they'd be willing to change the way their WebDAV server handles query strings (by just ignoring them—versus returning 404, as it was doing at the time). The CEO subtly reframed the conversation as if I was accusing them of not following the standards. I wasn't. Git utterly screwed up how it does content negotiation. The change on their end would have made it easier to upload content into the file storage/web hosting space included with all plans[1] using git instead of a dedicated, conventional WebDAV client or the flaky support built into nautilus. I explained that I had originally planned to write a blog post about another one of the benefits of a Fastmail account, but the smugness and passive aggression of Bron's subsequent response—"Oh good. We don't want that," and his likening the use of git to push your static site to Fastmail's web hosting as akin to abusing DNS to tunnel arbitrary IPv4 data (wat)—and the general intellectual dishonesty I'd run into over the years seeing them respond to criticism e.g. here on HN, along with the fact that my plan was up for renewal in a month made the choice not to renew (and to try to dissuade others from giving their money to jerks) an easy one.
I switched to a different provider the next month, ended up saving money, and have only ever been met with warmth and kindness in the interactions I've had since switching, which is now going on 10 years ago.
And they sent me an email explaining how grateful I should be, that I'm grandfathered in to being able to use my own domain on a "plan" they dont even offer., in a plan that didn't offer custom domains.
Well how'd I get all that then? I signed up for fastmail explicitly because $5/yr for custom domains.
Anyhow if you pay a host you're probably fine. Or find someone with an old /24 thats had a /31 or /32 unused for a long while, and no other black marks against the /24. And use that IP, set up demarc and all the other new email DNS stuff.