[Aachen]

I had spam bounces coming from Microsoft. Someone had convinced MS that they owned my domain and was apparently sending spam via an MS SMTP server (failing SPF was apparently not a problem for them), and any that bounced were being sent to my server: the real mail server for that domain. I reported the malicious org and explained what I had found out, but they obviously denied that it could possibly actually come from themselves and misunderstood what was happening (took me a bit to puzzle that out as well, those mystery emails showing up in my inbox). MS sending out spam isn't my problem, but I figured I'd be nice. Alas.

Few months later, they started bouncing my server's new IP address and that, too, wasn't their fault of course: "we're not seeing a block for your IP address so there cannot be bounces". Denying reality is super effective. The punchline was that they had blocked the new ISP's whole range rather than just my IP, so they weren't getting any hits when searching for my IP address. I found this out through some back-and-forth with a friendly sysadmin at the ISP, who was also banging their head against MS' wall...

These people must be so underpaid they're probably giving MS money for the privilege to work for such a correct business