I get spam from Microsoft IPs, using my own domain. Someone signed up my domain with MS. Of course I let MS know, figuring this must be some vuln in their syste

I get spam from Microsoft IPs, using my own domain. Someone signed up my domain with MS. Of course I let MS know, figuring this must be some vuln in their system or at minimum a clear-cut case of abuse they can shut down. They sent back a template saying it's spoofed. As if I can't tell the difference between a From/Received header and the actual remote address that was delivering this garbage to my own mail server. All of this I already made clear in the original email. Next up is Microsoft straight out rejecting email from my new IP address. It's not on any blacklist, it never did anything wrong, it just hasn't sent email before. Their systems for getting off the blacklist are somewhere between obscure, untouched for decades, broken, and nonexistent, depending on which page you look at and who you ask. Employees, if you get that far after hours of searching, claim my IP isn't blocked (yeah, right... they've blocked the range and so the employees can't find the IP ban, as if I'm supposed/able to know what bounds their range ban has.) The furthest I've got is that they somehow disable delivery failure notifications for a few weeks to shut me up but email still doesn't arrive. I'm rather done dealing with Microsoft of late.