Hi Curtis.
Unfortunately, warming up the new IP won't be painless.
It's not just a matter of PTR, SPF, and reputation.
The big email providers (Microsoft first and foremost) will block it as soon as they see the new IP, even if it has a good reputation and is clearly associated with a domain they already know, after receiving significant traffic from the new IP (I have no idea what the limit is).
presumed culprit :-(
You'll have to open the usual ticket; they'll respond with an automated system, and you'll respond to that too. At that point, they'll unblock you. Unfortunately, it will take a few days. :-(
So, when the time comes, have a known IP ready to divert outgoing traffic to MS domains and anyone else who does the same.
Sabatino Traini
Chief Information Officer